Part 1 of 2. In the Season 3 premiere, it's months after Peter's death and Megan returns to work, only to learn she's been teamed with a detective with whom she has a past history. She, Det. Sullivan and his rookie partner are up against a serial killer who targets young war veterans. The stakes become higher after she gets a call from the killer and is told he's holding her teenage daughter, Lacey, hostage.

In conclusion of the two-part Season 3 premiere, Megan discovers why the serial killer targeted war veterans, but must keep the information to herself or risk the life of her daughter, who is being held hostage by the assassin. Meanwhile, District Attorney Dan Russell has a run-in with Kate.

Megan and Tommy investigate a murder that appears on the surface to be a case of severe child abuse. But the girl's parents claim that their daughter was killed by the Devil after being possessed. The team must try to separate fact from fiction when the victim's mother begs Megan to help her stop the same thing from happening to their surviving daughter.

After his son is gunned down, a New York City mob boss threatens revenge, and when an early suspect is found dead, Megan and her team begin to believe the carnage has just begun.

After a murder suspect escapes from a prison-transport van, a witness in his trial turns up dead, and while Megan is investigating, the fugitive makes contact and tries to convince her that he's innocent and being framed.

Kate becomes involved with a man she met at a political event, but when a young Russian girl is found dead, she suspects that he may have something to do with the murder, and looks to Megan for help.

A murder victim's rabid neighbor bites Tommy, and after another rabies fatality, Megan calls on the new health commissioner to aid in their investigation.

When a young girl is found murdered, Megan has to put her personal doubt aside and help a blacked out Tommy, covered in blood, prove his innocence.

Gerry Roberts, in trial for defrauding his investors of a billion dollars, is kidnapped in front of the court house. The getaway car runs over a protestor and later, the team has to decide whether a video of Roberts being killed could have been faked by himself. Meanwhile, Megan gets closer to the truth about her father's death.

When a plane crashes in Philadelphia due to a gunman opening fire while aloft, the entire team of Megan, Kate, Tommy, Adam, Curtis, Ethan, Riley and Stafford must go into disaster mode. Since the crash hits the city's main power grid, Megan must conduct autopsies on the victims during frequent blackouts, but then one of the bodies goes missing. Meanwhile, Tommy and Riley are in a serious car accident while trying to investigate.

An inmate violently escapes from a prison transport van and becomes a dangerous fugitive on the run in Philadelphia. Soon another man turns up dead - who's revealed to be a witness in the escaped prisoner's murder trial. Megan must continue to search for the truth in the original case when the accused murderer shows up and pleads with her that he is innocent and being framed.

Megan's father's exhumation uncovers more questions about what she always believed was a suicide, and her mother suggests she examine his patient files for clues about his death and that of a patient.