When a nanny, and the child she took care of, disappear from her employers' home after being fired by them, the team must determine if the nanny is a kidnapping victim, or a kidnapping suspect.

When a homeless woman disappears from a shelter, the team is forced to re-examine the case of twin brothers Greg and Rick Knowles. Five months earlier (Doppelganger), Greg Knowles had confessed to a series of brutal murders, but the team was always convinced that it was Rick who had actually performed the killings. When Greg is released from jail and exonerated of the crimes, the team has to work against the clock to prove that Rick is the guilty party and to save one twin from the other.

After postal worker Rosie Diaz goes missing during what seemed to be a regular workday, the team initially connects her disappearance to her cargo, which include $12,000 worth of the game Demon Storm, which all the kids were after. But when the team gets in touch with child protective services, they learn that Rosie recently had her foster children taken away after an anonymous abuse call. A search of her home uncovers a DVD containing child pornography, and the team starts to look at the case from another angle. Danny comments on Martin and Sam's obvious closeness, and wonders why they're keeping it quiet.

When Stephanie Healy doesn't show up for choir practice, the team heads in to investigate and soon learns Stephanie had recently had a fight with her boyfriend. While speaking with Eddie, the team is shocked to learn that Stephanie used to be Stephen Patrick Healy. Convinced that the truth to what is happening in Stephanie's present lies in her past, the team investigates who Stephen was. Vivian has trouble hiding her worsening problems from the team, and is upset that Martin has been talking to Sam about his suspicions.

The team adds a new member who already as a connection to one of the team as they search for a missing prostitute.

After therapist Gina Hill disappears, the team investigates and initially suspects that one of her patients may be involved. After discussions with Gina's fiancé and her own therapist, the team follows the trail of clues to a bartender named Vince with an unusual ability to get good women to do whatever he wants them to. Martin continues to struggle with his recovery.

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

After Breck Mulligan goes missing from the women's shelter he had been working at, the team is called in to investigate. Breck was originally assigned to work at the shelter as part of a his probation for drug related offences, but the plight of the women and children seeking help had gotten to him and he had continued to work for the shelter, even going so far as to sleep with rich older women to get donations to help the shelter. The team is surprised to learn how little faith Breck's family and friends had in him, discovering that his friends had staged in 'intervention' the night he went missing, trying to convince him to walk away from his new life.