One of Jane's tattoos sends the team to a remote location where they find themselves face to face with a dangerous criminal in a case that puts Jane and Weller's strained relationship to the test and threatens to expose Mayfair's secrets. Meanwhile, Patterson breaks the rules to solve a tattoo puzzle.

In the thrilling mid-season finale the team goes after a group of sleeper spies that have just been activated and race to stop a slew of assassinations.

After a tip reveals there's a mole within the FBI's New York Office, the team must hunt for the operative while facing extreme scrutiny from Inspector Fischer. The team's deepest secrets threaten to be exposed, and everyone is a potential suspect - but some, especially Jane Doe have more to hide.