Plot

Twenty years after a fungal outbreak ravages the planet, survivors Joel and Tess are tasked with a mission that could change everything.

2003. As a parasitic fungal outbreak begins to ravage the country and the world, Joel Miller attempts to escape the escalating chaos with his daughter and brother. Twenty years later, a now hardened Joel and his partner Tess fight to survive under a totalitarian regime, while the insurgent Fireflies harbor a teenage girl with a unique gift.—HBO

In 1968 a scientist worries of fungi mutation caused by global warming.

In 2003 Joel and his daughter Sarah have a breakfast in Austin, Tx. His brother Tommy joins them, the two are building contractors. The radio mentions something going on in Jakarta. Sarah goes to school but takes some cash from Joel's dresser. The seniors next door are friendly. It's Joel's 36th birthday.

Sarah is bored at school. The bell rings and she gets a city bus. She brings her dad's watch to a repair shop. Outside sirens wail and cars rush by. A nervous woman comes in and tells her to go home, the watch is fixed.

She visits the neighbors, they are making cookies. The eldest sits in a wheelchair with dementia. Sarah checks the DVD collection and borrows one, returning home. She notices the dog staring at the old lady. Outside fighter jets streak overhead. The news mentions a possible new street drug. Joel returns home after a rough day, he forgot the birthday cake. She gives him his repaired watch, Joel is happy. They watch the movie.

Joel gets a call, Tommy is in jail after a bar fight. Joel leaves Sarah and goes to bail out his brother. Later, Sarah is awakened by explosions and helicopters. She is alarmed her dad is missing. The TV has an emergency alert to stay indoors. The neighbors' dog arrives. The dog runs off, Sarah goes to the next door house. The house is quiet but blood is in the floor. Granny Adler has killed and is eating the other couple. Sarah escapes and Joel arrives in time, killing the raging senior. They get in their truck and head out at speed.

The men have heard it is a virus or parasite. Joel refuses to stop to help others, they hit a traffic jam and drive overland. They will try to get to Mexico. They head back to town to scenes of panic. An airliner crashes back down the street. Sarah is knocked out as the truck is overturned. Tommy tells them to head for the river. They see fungus zombies eating other people.

A soldier stops them and reports in. He gets orders and approaches with his rifle, Tommy arrives and kills the soldier but Sarah has been shot and bleeds badly. Joel is frantic as his daughter dies.

20 years later a young girl staggers toward Boston, a wall surrounds a quarantine zone. Soldiers retrieve the girl and bring her inside. A woman questions her and sees a scratch on her pant leg. A man gives her a needle injection. Elsewhere men put corpses into a bonfire. Joel adds the newcomer girl's bound corpse to the fire. The Fedra pay clerk gives him his scrip. Four people are hanged in public for violations. A soldier pays Joel for a bag of tablets from Atlanta. They deal for a truck battery. The soldier warns Joel the guards are jumpy and tend to shoot first. What's left of the government is a hardline fascist organization called Fedra.

Tess complains to a man he cheated her on the truck battery. An explosion blows In the wall killing the other men, Tess manages to stagger out. Fedra troops are shooting and take her prisoner.

In a house a girl calling herself Veronica is in chains and forced to count to prove her mental ability.

Joel goes to see a man with a ham radio. There have been no messages from Tommy in three weeks. Tommy is in Wyoming. Joel stomps back to his flat, he gets out his maps and plans a route to Wyoming. He naps until Tess arrives, she reports in, the battery deal went south and they lost the money.

Marlene the Firefly leader goes to her CP. The others are losing faith with the Rebellion. Marlene plans an action, they need to distract the Fedra away from one area.

Tess has tracked down the battery location. The girl fights her chains. Marlene comes to see her, unlocks the cuffs. Marlene says she put Ellie in the Fedra orphanage as a baby. They will all be leaving that night. Marlene reveals a secret.

Tess and Joel look for the battery, they come across a dried fungus growth. They climb a ladder. They come out on a floor with recently dead men. The battery is there but is useless. Ellie suddenly attacks Joel, he fends her off. Marlene and her 2IC are there, both wounded, they were the other buyers for the battery. Marlene tells Joel and Tess to get Ellie to another group at the old State House.

The three walk back to Joel's apartment, Tess locks Ellie in a bedroom. Ellie finds a radio and a thick book of pop song hits. Joel has a nap, Ellie notices his broken watch. They chat, Joel wonders who Ellie is. Tess returns from a recce and they head out despite the curfew. They get out of the QZ by a tunnel. They make their way out of the buffer zone. A soldier stops them, it is Joel's drug customer. He orders them on their knees and won't make a deal. Ellie stabs him, Joel attacks in a rage and punches the man to death. Tess sees Ellie has a scar on her arm, Ellie says it is three weeks old, the three get to safety. Back in the apartment the radio plays an 80s tune.