'The Blacklist' episode 21: 'Berlin' is a person, but who is he?
What does happen is that Liz is ready to resign and give Reddington over to the FBI for full prosecution for his crimes (he has had immunity so far as part of his deal with the taskforce).
However, as she starts digging into the files on Reddington, she realizes that many of the people they've brought down courtesy of Red's list are people who are connected and out to get him, courtesy of "Berlin," who is not a place -- he's a person.
Over the course of the house, the FBI team manages to thwart the plans of Dr. Nikolaus Vogel at the behest of "Berlin" and a plane containing said mastermind goes down in New York.
There weren't many answers. In fact, the entire thing felt very much like spinning our wheels waiting for the big reveals to happen in next week's finale. But by episode's end, "Berlin" is presumably in the downed plane, Reddington and Liz are "stuck with each other" and Tom Keen has been outed to the FBI.
Next week is the big showdown between Red, Liz and Tom, plus hopefully we'll find out who "Berlin" is and what exactly he wants.
Tom: "You don't choose Berlin. He chooses you. And he is coming."
Reddington: "It made nearly dying well worth it. That's how I feel now."