As a young boy, Abe Applebaum, portrayed by Adam Brody, was a celebrated figure in the town of Willowbrook, known for his knack for solving minor mysteries as a "kid detective." However, everything changed when his close friend, Gracie Gulliver, vanished without a trace when he was just twelve years old. Despite Abe's dedicated investigation, neither he nor the authorities could uncover her whereabouts, leaving a lasting scar on him.
Now at the age of 32, Abe continues to run his detective agency, yet he faces skepticism from his family and ridicule from his peers for his apparent inability to mature and adapt to adult life. Struggling with his failing business and the absence of respect, he turns to alcohol and drugs as a means to cope with his depression. His mundane life takes a turn when Caroline, an orphaned high school student, approaches him, seeking help in uncovering the truth behind the murder of her boyfriend, Patrick Chang.
Abe, despite lacking experience in murder investigations, views this as an opportunity to redeem himself and accepts the case pro bono. Their pursuit for answers leads them to unearth multiple hidden truths about Patrick, including his involvement in drug trafficking and a secret relationship with an older girl named Melody. They also discover that Patrick's friend, Calvin, harbored feelings for Caroline and resented their romance.
However, Abe's investigative methods are clumsy, resulting in multiple blunders such as inciting anger from Patrick's father and even getting arrested for trespassing at Calvin's house. A breakthrough comes when Abe realizes that a series of origami roses, which Caroline believed were from Patrick, bear a striking resemblance to those received by Gracie shortly before her disappearance. Further complicating matters, Abe learns that a childhood assumption he made about a school fundraiser theft—wrongly implicating an innocent person—was also misguided.
With this new information, Abe connects the dots and uncovers the identities of both Gracie's kidnapper and Patrick's killer: Principal Erwin, who had developed an unhealthy obsession with Gracie. During a tense confrontation at Erwin's residence, Abe reveals his findings. It becomes evident that Erwin had not only stalked and kidnapped Gracie but had also left her child, Caroline, at a church after a horrific act of violence. In a tragic twist, Erwin had misidentified a revealing photograph of Melody in Patrick's locker as Caroline's, leading him to murder Patrick in a fit of rage.
Facing the truth of his heinous crimes and realizing he killed an innocent person out of a terrible mistake, Erwin takes his own life in front of Abe. In a shocking conclusion, Abe finds Gracie, alive yet imprisoned in a shed on Erwin's property.
Celebrated as a hero for solving the case and reuniting with Gracie, Abe regains the respect of the community and sees a boost in his business. Nevertheless, the traumatic events weigh heavily on his conscience, leaving him emotionally fractured. In a poignant moment, he breaks down in tears when his parents come to check on him, marking a profound end to this gripping tale.
