Deus Ex Machina (Person of Interest)

"Deus Ex Machina" is the 23rd episode and season finale of the third season of the American television drama series Person of Interest. It is the 68th overall episode of the series and is written by executive producer Greg Plageman and co-executive producer David Slack and directed by co-executive producer Chris Fisher. It aired on CBS in the United States and on CTV in Canada on May 13, 2014.

The series revolves around a computer program for the federal government known as "The Machine" that is capable of collating all sources of information to predict terrorist acts and to identify people planning them. A team, consisting of John Reese, Harold Finch and Sameen Shaw follow "irrelevant" crimes: lesser level of priority for the government. In the episode, Finch and other people involved in the Northern Lights project are being put on trial by Vigilance. While Reese and Hersh try to locate them, Root and Shaw work in order to avoid Samaritan's activation. The title refers to "Deus ex machina", a plot device whereby a seemingly unsolvable problem in a story is suddenly and abruptly resolved by an unexpected and unlikely occurrence.

According to Nielsen Media Research, the episode was seen by an estimated 10.95 million household viewers and gained a 1.9/6 ratings share among adults aged 18–49. The episode received critical acclaim, with critics praising the writing, acting, ending and the new focus for the next season.