One of the Russian spies from many episodes ago is back and is going to reveal a Russian mole in the FBI to a judge but is killed by her lawyer before she can tell. This causes Office of Professional Conduct Agent Fischer to return and investigate the team. He interrogates everyone but fingers Jane as the mole. It doesn't help that a Russian embassy asset confirms Fischer's finding. Weller is the only person who believes Jane is innocent so de "interrogates" (aka slams up against a wall and screams at) the embassy asset. The asset finally tells the truth, that Agent Fischer is the Russian mole. Weller rushes off to Jane, who has already been taken. Jane manages to free herself and shots Fischer. She says he was going for his gun but nonetheless, he is dead and Jane is free again.
While this is going on Reade finally tells Weller that he is dating Sarah, Weller's sister. Weller demands it end immediately. When Sarah confronts him about it, he freaks out on her. Looks like Weller isn't handling Jane standing him up very well. Jane on the other hand has decided to not trust Oscar anymore and says that she is no longer going to help him. Zapata also appears to being watched by someone. When she calls them out, they call her. No clue what is going on there.
The big bomb this episode is that Reade and Mayfair think that Jane is somehow involved in CIA Agnet Carter's death. They agree that Fischer's narrative was completely wrong but there are still holes in Jane's timeline and alibi.