Plot summary
The new number is a man named Chase Patterson ( Zachary Booth ). Finch, Root and Fusco are then to work on a case between the two gangs of Elias and Dominic while Reese works on Chase's case regarding the death of Chase's whole family. When Reese asks about the file regarding Chase Patterson, he finds out it was a case of Carter's ( Taraji P. Henson ). As Reese dives into the case, different flashbacks are shown with Carter doing similar investigation to what Reese is doing. As Reese reaches the final destination to the case, he discovers that Chase did not kill his parents and sisters.
It was Gil, the doorman at their building, as well as Chase's half-brother. Gil then shoots Reese but Reese manages to shoot him back, killing him. In the process, Reese is trying to escape, the slow process of death is shown with Carter. Reese, now hallucinating and succumbing to hypothermia, talks to Carter about things that he wished he could have talked to her when she was alive. After Reese finishes talking with Carter, she disappears from his hallucination, and a car pulls up.
Credits
Adapted from Wikipedia contributors, Person of Interest season 4. HTML formatting and reference markers removed.