Berto Colon

When they are given the Social Security number of a teenager who was killed two years ago, Reese and Finch begin to question the infallibility of The Machine. Meanwhile, Finch flashes back to The Machine's origin and how it was developed.

In the wake of several gang related child abductions, Intelligence must race against time to find a kidnapped boy. Owing to their swiftness and military precision, the team scours the VA records and tracks the suspects to a former Army Ranger. With his previous experience as a Ranger, Halstead (Jesse Lee Soffer) convinces Voight (Jason Beghe) to send him undercover to try and get information from inside.

Intelligence tracks down a vigilante killing rapists. The investigation hits home for Burgess (Marina Squerciati), who begins to question if the men who attacked her sister truly paid for their actions.

When Alicia's key witness commits suicide, she must turn to the only person whose testimony can salvage her case: Colin Sweeney. Meanwhile, Eli makes big moves on Peter's behalf.

Danny and Jackie are assigned to protect a key witness in a Russian mob trial, but when an attempt is made on her life, they realize there is a leak on the task force. Meanwhile, Erin is offered a job as deputy mayor, which would have her working directly with her father.