28 Years Later opens on the day the Rage Virus first ravaged the UK, with a young boy named Jimmy fleeing to a nearby church when the infected attack. His father, a priest, believes this is judgment day, and allows himself to be devoured as his son hides in a crypt and survives.
The movie then jumps ahead to, you guessed it, "28 Years Later." Europe has managed to contain the virus, but the UK has been put into a permanent quarantine. The waters are patrolled by NATO military ships, and anyone left in Britain must stay there and is left to their own devices.
Much of what follows revolves around Spike (Alfie Williams) and his father, Jamie (Aaron-Taylor Johnson). Along with Spike's sick mother, Isla, they've taken refuge on Holy Island, but he and Jamie must leave her behind to travel to the mainland so Spike can kill his first infected. It's like a rite of passage.
They encounter the military and an "Alpha" zombie, a massive infected that leads the others. Returning home, Jamie greatly exaggerates his son's success and has sex with another woman. Seeing this, a furious Spike confronts his father and sneaks his mother out of the settlement so he can get help from the demented Dr. Kelson (Ralph Fiennes).
Mother and son encounter a pregnant infected, who gives birth to a baby not affected by the Rage Virus. Meanwhile, Dr. Kelson confirms that Isla has terminal cancer and can do nothing to help her. He offers a painless way out, and she agrees. With that, he drugs Spike and euthanises her.
The next day, the doctor presents Spike with his mother's skull, and the boy places it atop the pyramid of them outside. After helping Dr. Kelson escape the wrath of an Alpha, he returns home with the baby, named Isla, and leaves it outside the gates with a note.
The boy returns to the mainland as his frantic father screams his name, to no avail. In the movie's final scene, Spike is at a campfire and confidently kills an infected (he's no longer the scared child he once was). More arrive, and it's then that an adult Jimmy (Jack O'Connell) shows up.
He leads a cult-like group and wears his father's crucifix upside down. Congratulating Spike on his success in holding off the infected—the rest of the cult kill them in a bizarre, violent ritual—Jimmy offers him a place in the group as the credits roll.
28 Years Later: The Bone Temple will likely explore Jimmy's story and the role of his group in what remains of the UK. Earlier in the movie, Spike and Jamie find a body hanging upside down, with the letters J-I-M-M-Y carved into its chest, so they're clearly a twisted bunch whose motivations, thus far, aren't clear.
With this new trilogy, filmmaker Danny Boyle appears to be setting out to explore what becomes of humanity while facing the infected, and how it changes them into monsters, along the way.
28 Years Later doesn't have a post-credits scene, so we'll have to wait and see what filmmaker Nia DaCosta does with The Bone Temple, and how her follow-up continues Spike's story (and ultimately sets the stage for Cillian Murphy's return as Jim, a character who doesn't appear in this opening chapter).
28 Years Later is now playing in theaters.