David Haller is being interrogated by government officials who believe he may be the most powerful mutant discovered. He explains that he was diagnosed as schizophrenic when he was young, and was taken to Clockworks Psychiatric Hospital after attempting to commit suicide. He spent six years as a patient there, during which time he met Sydney "Syd" Barrett, a girl who refused to be touched. She agreed to be his girlfriend, but was eventually discharged from the hospital. Before she left, Haller kissed her goodbye, causing their minds to switch bodies. Losing control, Syd unleashed abilities from Haller's body that killed his friend Lenny Busker and trapped the other patients in their rooms. Haller was evacuated in Syd's body. Later, Haller's body returned to him, and he went looking for Syd. Haller found himself being chased by two people until he was captured by the government. Now those two people, Ptonomy Wallace and Kerry Loudermilk, break into the government facility with Syd to rescue Haller and take him to Melanie Bird.
At Bird's facility Summerland, Haller begins "memory work" with Wallace, who remembers everything and can enter others' memories. Bird explains that Haller had been captured by Division 3, one of the government's divisions focused on capturing and studying mutants. Bird says that she instead wants to help Haller, by showing him that the onset of his 'illness' was just his powers manifesting. In Haller's childhood memories, he is haunted by a children's book his father read to him, The World's Angriest Boy in the World, in which the title character murders his mother. In his memories before his admission to Clockworks, Haller took drugs with Busker to try block out the voices he hears. Bird places Haller in an MRI scanner to study how his brain works, during which he accidentally projects his mind to present day Clockworks, where his sister Amy is looking for him. Amy is kidnapped by Division 3, causing Haller to panic and teleport the MRI scanner outside Summerland. Haller races to save Amy, but Barrett convinces him to wait and master his powers first.
David searches for answers, while a threat looms.
David's in trouble, while his friends search for answers.
David faces a new threat.
David goes back to where it all started.
David tries to find a way out of his predicament.
David faces his biggest challenge yet.