Gus, a young boy with deer features, lives a quiet life deep in the woods with his father. He learns many things, from medical care to religious prophecy. Though he loves his religious father, he yearns to escape as he learns that there is not fire past the trees, but simply more land.

Sometime after Gus' father passes from an illness, strange men come to capture him. They are slain by Jepperd, who then promises to take Gus to a sanctuary. Lonely, Gus goes with him. Along the way, they encounter many problems. Hybrid cultists almost kill Jepperd but Gus saves him. 'Sweet Tooth' then earns his nickname by eating all of Jepperd's candy/food stash though he had gained more food while Jepperd recovered. The duo also rescue several women from a prostitution ring.

Ultimately, Jepperd betrays Gus to a horrible scientific facility in return for the remains of his wife. It turns out a mysterious plague has been wiping out humanity, and the leader of the facility, Abbot, along with scientist Dr. Singh, believe the half-animal half-human children hybrids have something to do with it. In flashback we learn Jepperd was a former hockey bruiser who protected his wife Louise in the post apocalyptic world. Eventually though, Louise revealed she was pregnant and Jepperd relents when a militia, led by Abbot, offers protection. It was all a trick however, with Abbot and Singh experimenting on pregnant women and hybrid babies to try to find a cure for the plague. Jepperd is kept in a cage but is eventually freed by Abbot's brother Johnny, a guard in the facility. Johnny tells Jepperd his wife is dead, and Jepperd goes on a rampage through the facility. He is recaptured, and Abbot lets him out of the camp, telling him he can have his wife's remains if he brings Abbot a hybrid child. This was why Jepperd betrayed Gus, and he heads home to fulfill a promise to his wife that he would "bring her back home".

Gus, despite the horrors, makes friends with the last of the animal children at the place, the pig girl Wendy, half feral groundhog boy Bobby, and the silent donkey boy Buddy. Gus is hypnotized by Dr Singh, who goes deep into his memory to find out the truth about his birth. He discovers that Gus's father was a lunatic, and may even have been responsible for the apocalypse. He insists Abbot take him to the woods. They discover a bible that was written by Gus's father, but no evidence of a mother in her grave, on the way back to the camp, Singh starts to believe the writings. Jepperd, overwhelmed with guilt and a directionless life, decides to re-rescue Gus. He recruits Becky and Lucy, the women he saved, and hundreds of hybrid cultists. With help from Johnny, the children escape, although Gus is forced to kill a lost alligator-child who had gone feral. While on the move, Jepperd and Gus share an identical dream about Alaska.

A battle and the intervention of Johnny allow Jepperd and the women to escape with the children and Dr Singh, who insists on coming. Seemingly, Buddy is lost to the murderous attentions of the hybrid cultists... and at the same time seems to think Jepperd is his father. Despite the emotional turmoil, the group closes ranks to protect the children still with them. Buddy is taken by Abbot who murders the head cultist to do so. Somehow, the headmaster is now friendly and sympathetic towards the injured, moaning boy. Gus, Jepperd, Becky, Lucy, Wendy, Bobby, Johnny, and Singh stumble across a mysterious dam.

Ep.1. Out of the Deep Woods"Jim MickleJim MickleJune 4, 2021T15.10153
Doctor Aditya Singh goes to work one day and discovers a deadly virus is taking over the world. At the same time, hybrid children start being born that are half-human and half-animal, with no one agreeing which came first, the virus or the hybrids. Meanwhile, before the collapse of society known as the Great Crumble, a father runs away into Yellowstone National Park with his deer hybrid baby, Gus. Dr. Singh discovers that the first symptom of the Sick is an uncontrollably shaking pinky finger, and he rushes to the hospital to save his wife Rani who has that symptom. Gus' father, over many years, builds a secure base in the deep woods and is referred to by Gus as "Pubba". Pubba is constantly afraid of the outside world. But as Gus grows, so does his curiosity about the world, and one day he steps outside the fence to venture after the deer he believes is his "mother", despite Pubba's warnings about the outside world being fire and telling him that his mother is gone. Later, a man claiming to be looking for his sister arrives at the fence and tells Pubba that everyone in the outside world thinks the hybrids are responsible for the Sick which still exists after 10 years. After hiding Gus, Pubba kills the man but also contracts the Sick, which quickly kills him. In his frustration, Gus starts a daytime fire which attracts the attention of poachers who lay a candy trap that Gus easily falls for. Gus, however, is quickly saved by Tommy Jepperd who Gus calls "Big Man". While distrusting of Big Man at first, Gus eventually explains his plan to find his mother in Colorado using a map and a photo. He chases after Big Man to seek the latter's help with his quest.

2"Sorry About All the Dead People"Jim MickleJim Mickle & Beth SchwartzJune 4, 2021T13.22302The narrator introduces Aimee, who was a therapist before the Great Crumble and who barricaded herself in her office for weeks during the fallout. When she eventually emerges into the deserted city, she is passed by a stampede of elephants and is inspired to go to the Zoo which she makes her home. Gus persistently follows Big Man and insists Big Man take him to Colorado. Big Man gets angry when Gus eats all of his food and his medicine, the latter of which Gus says is horrible candy, but Gus leads them to a Visitor's Center from where he can smell food. At the Center they find living there a couple and their human son not much older than Gus. After being recognized as a former Last Man by the mother through the branding on his chest, Big Man insists that he only wants to stay one night to wait out the storm and don't want trouble. The father also recognizes Big Man as a former pro football player. Dr. Singh temporarily treats the Sick in Rani through experimental medicine provided by Dr. Bell. When he goes for a refill he discovers that Dr. Bell wants him to take over her work as she is dying from terminal cancer. She has noted down all of her findings in a book, but her gruesome work goes against everything Dr. Singh believes in. Big Man begins to think the family at the Center may be better company for Gus. But soon the Center is attacked by Last Men who Big Man kills with a bear trap, and the family asks Big Man and Gus to leave for fear their family might become collateral damage. Big Man and Gus continue on to the next town. Aimee discovers a hybrid pig baby outside the Zoo.

3"Weird Deer S**t"Alexis OstranderMichael R. PerryJune 4, 2021T13.22303Gus and Big Man continue on foot to the Market where there is a train that will take Gus to Colorado. Big Man disguises Gus as a human so they can get him on the train, but while purchasing him a ticket Gus wanders off and meets a young girl in the Market who comforts him when he panics. Dr. Singh takes over for Dr. Bell and starts working with the Last Men who provide him with supplies. He and Rani reluctantly attend a party where the host Doug is discovered to be infected. The house where the party was at is set on fire with Doug inside it to prevent the spread of the Sick. As he is about to board the train, Gus smells Big Man's medicine among the boxes being loaded, so they steal the supplies but are caught and Gus is exposed as a hybrid. The Last Men, while transporting Big Man and Gus through the forest, are ambushed by teenagers dressed as animals who kill the Last Men and rescue Gus and Big Man. The leader dressed as a Bear reveals herself as the girl from the Market. General Abbot is informed that "she has been found".

4."Secret Sauce"Toa FraserJustin Boyd & Haley HarrisJune 4, 2021T13.22304Bear instructs the group to shoot Big Man, but Gus protests, shocking the group with his ability to speak. Bear changes her mind about killing Jepperd, much to the displeasure of Tiger. Bear introduces Gus to their home in an abandoned theme park and tells him about how she is the leader of the Animal Army that has vowed to protect hybrids at all costs. The group gives Gus many things, like candy, and allows him to drive bumper cars, while Tiger continues to pressure Bear on why they haven't killed Jepperd yet. Bear says she wants to understand why Gus is protecting a poacher. The doctor continues to try to make medicine for his wife who has the illness, but is unsuccessful as he needs a live hybrid. The couple's nosey neighbor Nancie tells the Singhs she wants to hold a citizen's vote on mandatory virus-testing every week, worrying Dr. Singh who fears Rani will be exposed. Aimee raises the hybrid baby "Pigtail" as her own in the city zoo, scavenging and avoiding Last Men. One night, Aimee fears an intruder is in the building, but Pigtail reveals that it is her friend Bobby, an animal who can speak, and asks Aimee if they can keep him. Bear reveals to Gus that Big Man was once a Last Man and has hurt hybrids, but Gus doesn't care as he says Big Man is his friend, countering that the Animal Army has hurt people as well. At the execution of Big Man, Bear reveals she will not carry out the execution as it would hurt Gus. This leads to a coup led by Tiger who tries to proceed with the execution of Jepperd. Big Man and Gus escape, with Bear following as she abandons the Animal Army. Nancie discovers Rani has the Sick and plans to expose her, but as they argue in front of the Singhs' house she is kicked to death by their horse. The Singhs hide her body.

5"What's in the Freezer?"Robyn GraceChristina HamJune 4, 2021T13.22305General Abbot confronts Dr. Bell about her faking a terminal illness and demands to know the location of her notebook. She tells him she has left it with her replacement, Dr. Singh, and that the hybrids are just children who will be here long after the human race is gone. General Abbot has Dr. Bell executed. Jepperd thanks Gus for having his back at the Animal Army camp and says he will accompany him to Colorado. Bear finds Gus and Big Man and gives them Birdie's last known address. Bear also shows them a path to the railway for the train to Colorado, but the path goes through a Valley of Sorrows populated by the purple flowers that accompany the Sick. Gus, fed up with their continuous bickering throughout the journey, ventures out onto the rickety bridge that crosses the Valley of Sorrows. He falls into the purple flowers. Aimee and Pig Tail continue to build the Preserve for hybrids, but Pig Tail is discouraged she isn't as animal as the rest of the hybrids. The Last Men find and tag the Preserve. While unconscious, Gus encounters Pubba who tells him to be brave, that other hybrids are counting on him, and that the whole world will see him soon. Then, in the mirror where Pubba was, he sees General Abbot. Pubba warns him that Abbot is coming, but says Gus is ready now. Big Man and Bear rescue Gus from the flowers and Gus forces them to stop arguing. The Singhs continue to cover up Nancie's disappearance as people in the neighborhood declare her missing. Dr. Singh expects a hybrid delivery in order to save Rani who is deteriorating, but the Last Men deliver a note saying they are out of hybrids. The town discovers Nancie in the freezer, but Dr. Singh tries to convince them Nancie was Sick. Then Rani starts showing symptoms, so the town binds them inside and sets the building aflame. The Last Men and General Abbot save the Singhs.6"Stranger Danger on a Train"Jim MickleNoah Griffith & Daniel StewartJune 4, 2021T13.2230

6.Big Man, Bear, and Gus manage to board the moving train to Colorado but discover it is not a passenger train. The Singhs bluff that Dr. Singh is working on a cure that is not detailed in the book in order to convince General Abbot that he must spare both of their lives. On the train, Big Man encounters a friend and former pro football player named Jimmy "Fat Man" Jacobs who he initially fights in order to protect Gus before he recognizes him. Gus is distraught over the loss of his stuffed animal Dog that his Pubba made him and wanders off from the group. Aimee realizes they have been found by the Last Men and that the Preserve is no longer safe. While looking for Gus, Jimmy asks about Jepperd's wife, unborn child, and other friends who have all passed from the Sick. Jimmy also provides information about the location of Gus' mother Birdie, but neglects to mention that Last Men members are aboard the train. Big Man saves Dog for Gus by pretending to be a Last Man but blows his cover, so Jimmy holds the door for the group so they can jump off the train. Jimmy then fights the Last Men and is presumably killed for his efforts. Aimee, Wendy (aka Pig Tail), and the other Preserve hybrids pack and escape through the tunnels with Aimee remaining behind. Big Man, Gus, and Bear reach Essex County, with Big Man offering to Bear that she can stay with him and Gus if she wants.7"When Pubba Met Birdie"Toa FraserBeth SchwartzJune 4, 2021T13.2230

7. A flashback to an expedition to Alaska reveals something discovered in the ice rods which is packed up and shipped to Fort Smith Science Research where Pubba is shown to be working as a janitor. Pubba one day encounters Birdie in a bar where he reveals his name is Richard and apologizes for eavesdropping on her earlier conversation with Judy. Birdie reveals she is a geneticist and is upset because she was working on an important project but is now being transferred to a different department. Birdie tells Richard that she found a unique microbe for a vaccine that they have been testing on chicken eggs which could either save the world or go disastrously wrong, depending on the execution. Richard walks Birdie home where she invites him in. They grow close and almost kiss, but she gets a call saying the military is taking over the lab. Richard offers to assist her in breaking in to rescue her project. Gus, Bear, and Big Man get to Birdie's address only to discover that only Judy, Birdie's former coworker, lives there and that Birdie left 10 years ago to look for Gus. In a flashback, Birdie shows Richard the unexpected outcome from their project, which is the baby Gus. The name "Gus" stands for Genetic Unit Series. Richard distracts the military personnel long enough for Birdie to escape with Gus, but Birdie later asks Richard to take Gus so she can return to the lab to destroy her research. In the present, Gus goes through Birdie's files and is confused until Big Man finally tells him, based on the files, that he was created by scientists in a lab. Gus is devastated that he doesn't have any real parents and angrily runs into the woods.8"Big Man"Jim MickleJim MickleJune 4, 2021T13.

8.Flashbacks show that when the Great Crumble began, Big Man nearly abandoned his hybrid baby. He eventually changed his mind but before he could get back to his wife and son, the Last Men already took them. In the present, Gus finds an abandoned plane and uses its radio; believing that he is talking to the Preserve, he inadvertently gives his location to the Last Men army. Aimee fights against General Abbot and his Last Men army. She is able to escape, but the hybrids she cared for are captured. General Abbot captures Singh and Rani as well and forces Singh to begin working on a cure for The Sick. Big Man finds Gus and sits with him; however, the Last Men arrive, shoot Big Man unconscious, and capture Gus. Aimee arrives and retrieves Big Man's body, takes him back to her hideout and nurses him back to health. It is revealed that Aimee has been intercepting free-to-air radio communications of the Last Men army. When Big Man awakens, Aimee tells him to continue resting and declares that they will get their children back by whatever means. Back at the cabin, Bear recalls her childhood memories, revealing that Pig Tail was her foster sister, and also remembers when her family was taken by the Last Men. She later receives a communication from a phone and answers it, as the person on the other line is revealed to be Birdie, hiding in an Arctic area with her research.