Danny promises a child that he'll open a cold case, the death of his firefighter father. Meanwhile, Jamie saves a baby from a burning building but worries that his new-found fame as a hero in the press jeopardises his job.

The investigation into a girl's disappearance leads to a high-tech kidnapper who uses the internet to cover his tracks; Rollins reconnects with her sister.

As Sherlock is shocked by the reappearance of his former lover, Irene Adler, a series of flashbacks reveal the tumultuous events that led to his downfall into addiction.

Sergeant Voight and Detectives Lindsay and Halstead work with the SVU to investigate the roots of a child pornography site; tension between Benson and Voight threatens the investigation.

After a single mother is arrested for leaving her young daughter alone for days, Sergeant Benson suspects the woman may have been abused in her own childhood.

While Carter closes in on Reese and Finch and the CIA close in on her, the two men investigate a suspicious building supervisor whose number has come up.

Danger mounts for Elizabeth and Philip as they get closer to the inner circle of the CIA Afghan Group; Stan monitors Zinaida; Agent Aderholt challenges Agent Gaad on a crucial operation; Arkady tasks Oleg and Tatiana with gathering intel.

Elizabeth and Philip come together to deal with a mission gone wrong, but struggle to reconcile their ideologies; Stan welcomes a Soviet defector to America; Nina acclimates to her new living arrangements.

When the situation with Tuan takes an unforeseen turn, Philip and Elizabeth are thrown off track; Henry makes a surprising proposition; Stan encounters Frank Gaad's widow.

Hank and Divya treat a veterinarian; Evan and Paige help a friend deal with loss; Boris must make accommodations.

Jimmy attempts to settle his debts; Nacho reunites with an old acquaintance; and Mike helps Stacey with a project and makes a meaningful connection.

Jimmy is pushed to desperate measures; Nacho picks up a new skill; Mike explores an alliance; and Kim stands up to Hamlin.

The CIU take a look at the case of a controversial political activist serving a life sentence for bombing a mosque.

Sherlock reels when his former lover, Irene Adler, reappears; Sherlock and Joan are caught in Moriarty's crosshairs.

Michaela and Saanvi share a vision that leads them to a stowaway; Jared takes the fall for someone else; Ben comes face-to-face with his replacement.

Ben struggles to trust a journalist who wants him on a Flight 828 podcast; Michaela hallucinates; Olive invites Danny over for dinner.

Michaela is conflicted when she comes face-to-face with her best friend, who is also Jared's wife; Ben hears mysterious music in his head, moving him to help a fellow Flight 828 passenger reconnect with his son.

Captain Daly asks Ben to help clear his name and prove he's not responsible for the disappearance of Flight 828; Michaela unwittingly puts her family in danger when she allows a traitor into their home.

After a member of the president's staff is murdered, Ellen urges Duncan to back out of the assassination plot, when the president's staff take matters into their own hands.