As Martin tries to recover from near-fatal gunshot wounds, Danny suffers from post-traumatic stress disorder. Meanwhile, Elena Delgado, a former New York police officer, joins the team, and events follow.
In the fifth season, Samantha's troubled past, including her heated connection with her mother, Patricia, is further explored. Anne and Jack's relationship ends after her miscarriage, and Elena's ex-husband Carlos files a lawsuit to get custody of their daughter and subsequently kidnaps her.
In Season 6, Jack Malone disappears after taking on a dangerous case by himself, but he and the other committed detectives in the Missing Persons Unit keep working on solving new murders.