A 12 year old boy (Jake Thomas) goes missing. The team discovers that the boy had a rough 24 hours leading up to his disappearance. He disappeared in the middle of the school day, the only clues a broken miror, a discarded hall pass, and blood on the wall....until a picture of him is sent around the school.

Chet Collins has been searching for his son since the boy was kidnapped four years earlier on a camping trip, and is the one case that Jack has never been able to forget. When Chet disappears, leaving behind only his wedding ring and the mountains of debt he had accumulated in his search, Jack will go to any lengths to find Collins and save him from himself.

After young Shawn Hopkins disappears one night after leaving the arcade, his parents soon begin to believe that the team is not doing everything to find their daughter, and are shocked to learn that their son has been gambling and has also been seen with a local drug dealer. After learning that Shawn had taken up the cause of a friend who had been raped, Larry and Susan Hopkins are relieved to learn that their son wasn't doing anything wrong, but worried that he still might not come home.

When the team tries to plot a strategy after they find out that Samantha has been shot and that she might be critically injured in the hostage crisis situation. Jack makes a deal with Berry so that Sam can get help and Jack goes in there and takes Sam's place.

With the aftershocks of Sept. 11 and man named Barry , who lost his wife that day and then his job soon after. The man lashes out at her former boss an employment-agency owner. Blaming her for his wife's death and his own failure to find a job, Barry kidnaps the woman for ransom.Then he demands the money be exchanged at a bookstore, but when the cash is delivers Berry is provoked and takes the store's patrons hostage. Among them is Samantha,and given Jack's affection for her complicates the negotiations.

When a man leaves his home in the morning with his daughter to take her to school and then to open his dry-cleaning store, but they both of they never make it there .

Malone searches for a missing woman whose description matches those of a series of murder victims from a 12-year-old case only to learn that Graham Spaulding is pulling the strings, and drawing on incidents in Jack's past to lure him into a trap.

After telling his mother, he wanted to leave school for good, seventeen year old Andy Deaver vanishes from his private boarding school, last seen by it's headmaster, Graham Spaulding.

Annie Miller disappears on her way to school. The group looks into her disappearance, with their suspects ranging from the local mayor, to Annie's godfather, all the way to a young man working for the father of her best friend. Twenty-four hours after Annie's disappearance, her best friend Siobhan Arintero also vanishes, leaving only a collection of videos to help find the two girls.

When Sam helps Martin search for his missing and terminally-ill aunt, they discover that she's been using her nursing skills to assist other dying patients in committing suicide; his father's Alzheimer's diagnosis prompts Jack to attempt a reconciliation.

When a father who goes missing while trying to prove that his son a death-row inmate who is scheduled to die in two days is innocence, The past 11 years of the missing Mans life have been devoted to proving that his son, was wrongly convicted of killing a young married couple in front of their daughter during a convenience story robbery. While the team does not rule out that the despondent man could have brought harm upon himself, the team members find themselves wondering if the man is right about his son innocence.

The team worries about a grieving father who couldn't accept his daughter's death, especially after child pornography is found in his home.

Jack and the team search for a pregnant woman, Kathy Dobson, who disappeared from a hospital before being told that she has serious complications. As the detectives race against time to find Kathy, their investigation gradually reveals that Kathy's seemingly happy life actually hasn't been going very well. She is eight-and-a-half months pregnant and, under the tight control of her husband Paul, has withdrawn from her family and friends. Paul's brother Ritchie, who has been following Kathy and providing Paul with addresses she visits, lists a woman who may be affiliated with an ""underground railroad"" that helps battered women. When the team members find the woman, they learn that she has been assaulted by Paul—but she still refuses to lead them to Kathy.

To find a missing young mother who was recruited as a drug mule, Samantha goes undercover to lure the drug trafficker who recruited the young woman.

The team tries to track down a reclusive columnist who hadn't left her apartment in months and was communicating with numerous prisoners.

Bryan Parker is questioned by the FBI after being found alone on the road by a police officer, his hand bandaged. He tells them about a young boy his father had abducted, and soon the team is searching for Todd. The search initially goes nowhere, and Sam continues to question Bryan, but they get a lead when Bryan identifies a snapshot of the boy that reveals his identity to be that of missing boy Daniel Ellison. It isn't long before the squad realises that Daniel isn't the first boy that Parker grabbed, and follow his past to find him and the missing boy.

Jack's methods for investigation of child molester could result in the case being kicked out of court. Then on top of that, the Office of Professional Responsibility decides to investigate the team, but their real target is Jack

The team investigates a missing woman's boyfriend, with whom she lived. However, they determine that he has a twin brother and quickly turn their attention to him.

A young mother disappears after leaving her three year old son with a babysitter.

Jack finds himself in the hotseat when a young white woman and a young black man, go missing on the same night and Jack is ordered to put more of the team's resources into finding the young woman.

The team uncovers a history of deception as they search for a man posing as a college student vanishes.

While working on a high profile civil case, a trial consultant vanishes. Jack and Sam learn how to make adjustments as Brian and Finn spend more time together.

Third-year-resident Anwar Samir vanishes from the hospital he works in. Because of his Saudi-Arabian background, suspicions of terrorist links arise.

A girl vanishes from a psychiatric hospital, and it appears she may have escaped with a staff member. Then the team learns of a troubling incident from her past that may hold the key to her disappearance.

When a high school sex-scandal leads to murder it is the team's job to figure out who did it and why.