Into the abyss explores a triple murder which occurred in the small Texas City of Conroe in 2001. Michael Perry and Jason Burkett, under the influence of alcohol and drugs, murdered a middle-aged housewife; they then gunned down her stepson and his friend. The film features Conversations with the two inmates and those affected by their crime. Unlike many of the films that deal with crimes, into the abyss isn't concerned with figuring out exactly what happened, but rather serves as an examination of why people - and the state - kill.

Dr. David Gale, an advocate of eliminating the death penalty, is falsely accused of rape and murder. Once convicted, he ends up on death row in Texas himself, telling his story to a reporter through a series of flashbacks.

In Seattle, the successful forensic psychiatrist and college professor Jack Gramm is in evidence since he was responsible for the condemnation of the serial killer Jon Forster, influencing the jury to sentence him to the death row. Jon accuses Jack of manipulation, inducing one witness and sister of one of his victims to testify against him. On the eve of Jon's execution, Jack receives a phone call telling him that he has only eighty-eight minutes of life, while a killer is copycatting Jon, killing women with the same "modus-operandi" and is investigated by Seattle Slayer Task Force. With the support of associate Shelly Barnes, an FBI agent, his friend Frank Parks, and his assistant Kim Cummings, Jack investigates some weird and problematic students, a security guard of the campus and the woman with whom he had one night stand.