Thr3e by Ted Dekker is a Christian psychological thriller that follows the main character of Kevin Parson. Kevin is introduced as a seminary student who is writing a paper on evil and human nature; when the novel opens, he is discussing this subject with his philosophy professor, Dr. John Francis.

On his way home from the seminary, Kevin receives a mysterious phone call from a stranger named Richard Slater. Slater’s demand is that Kevin “confess his sin” to the newspapers in the next three minutes. If Kevin does not, Slater claims he will cause Kevin’s car to explode. With no understanding of what “sin” Slater is referring to, Kevin fails to meet the ultimatum and narrowly escapes with his life as his car explodes.

Slater continues to contact Kevin with riddles and bomb threats, always giving him clues related to the number three. Confused and overwhelmed, Kevin informs the police, and the FBI becomes involved. Kevin also calls his childhood friend, Samantha Sheer, who promises to offer any help she can and even comes to town to support Kevin. However, amid this show of love and concern, Slater continues to call and demand that Kevin “confess.”

Together with the FBI—specifically an agent named Jennifer Peters, who believes that Slater may be responsible for the death of her brother and is therefore even more eager to catch him—Kevin and Samantha work to figure out exactly what Slater wants from Kevin. Through this process, Kevin is forced to relive much of his traumatizing and abusive childhood as he struggles to remember what could possibly be the “sin” upon which Slater is so fixated. Their search includes returning to Kevin’s childhood home, where he lived with his aunt Belinda after the death of his parents, and getting locked in several places by Slater, who always seems to know where they are and what they are doing.

Kevin is deeply conflicted about his relationship with his aunt, and Jennifer soon uncovers troubling facts about Kevin’s childhood with her: Belinda shielded Kevin from anything of which she disapproved and stunted his development in order to avoid shaming her son, who had an intellectual disability. Forbidden from playing with other children, Kevin was only able to befriend Samantha by sneaking out of the house at night.

Eventually it is revealed that when Kevin was eleven, he was bullied by a boy named Sam, whom Kevin locked in a warehouse and left for dead. As the riddles and threats continue, Kevin realizes that Sam must be the true identity of Richard Slater. He confesses his “sin” to the media, as Slater has been demanding, but the threats do not stop. Slater ultimately kidnaps Belinda and forces Kevin to choose between killing her or killing Samantha.

Toward the end of the novel, the reader discovers, along with Kevin, that both Slater and Samantha Sheer only exist within Kevin’s own mind. Thus, the number three is given a deeper meaning because it is the number of Kevin’s personalities. This trio is representative in many ways of ultimate good (Samantha), ultimate evil (Slater), and the struggling soul in between (Kevin). The realization of these three characters existing within one body changes the entire plot arc of the book, and Kevin seeks treatment for his condition.