Plot summary
The new number is Congressman Roger McCourt ( John Heard ), who serves on the powerful Rules Committee. The team is initially baffled: He has no obvious enemies. They eventually discover a connection to Decima: McCourt admits to agreeing to help Decima with favorable legislation (granting Decima access to government surveillance feeds), in exchange for insider stock-trading tips. Reese concludes that the team is the “danger”, because the Machine wants them to kill McCourt in order to prevent future killings by Decima. Harold is deeply disturbed at this idea, and he leaves the team, not wishing to participate in an assassination.
In the end, McCourt is left alive and proceeds with Decima's plan. Greer also approaches a skeptical Senator Garrison, offering him a 24-hour beta test of their machine. Garrison agrees, and Greer immediately deploys Samaritan to track down Finch. Meanwhile, Root is travelling across the country, dealing with various relevant threats.
Credits
Adapted from Wikipedia contributors, Person of Interest season 3. HTML formatting and reference markers removed.