On this week's Person of Interest...

With Samaritan online, Decima seeks out Finch as well as tries to eliminate Reese and Shaw.

Root helps Reese and Shaw avoid getting killed, even as the two decide to take on a number: Grace.

Decima goes after Finch’s love Grace in an effort to draw Finch out.

Finch decides to trade himself for Grace, but instructs Reese to kill all of Decima if she is harmed.

Greer sits down with Finch for a talk.