Black Bag Ending explained: who is the traitor?

Michael Fassbender is on the hunt for a traitor in Steven Soderbergh’s spy thriller Black Bag. But with a star-studded list of suspects that include Cate Blanchett, Pierce Brosnan, Rege-Jean Page, Naomie Harris and more, just who is the traitor and what were they trying to do?

We’re obviously going to get into some Black Bag SPOILERS as we go into depth on the movie to answer those questions for you, so if you have not, here’s how you can watch Black Bag right now. As I make clear in my Black Bag review, I recommend that this is one you're not going to want to miss or be spoiled by.

Black Bag begins with George Woodhouse (Fassbender), a brilliant intelligence agent, receiving information that a dangerous device known capable of killing thousands of people has been stolen and that there are five suspects within his organization that are the primary suspects. One of them is his wife, Kathryn St. Jean (Blanchett). Over the course of the next week George must try to determine who the traitor is and retrieve Severus before it can land in the wrong hands.

In addition to Kathryn, George’s lineup of suspects include Col. James Stokes (Rege-Jean Page), Freddie Smalls (Tom Burke), Clarissa Dubose (Marisa Abela) and the agency psychiatrist Dr. Zoe Vaughn (Naomie Harris); adding to the intrigue, both Stokes & Zoe and Freddie & Clarissa are sleeping together, though the relationships have issues. George is an expert at finding the truth, but how will that work against a group of fellow spies? And if signs begin pointing to Kathryn, what will George do?

When George finds a movie stub in Kathryn’s waste basket of something they haven’t seen together, George can’t help but become suspicious. He finds out that she is heading out of the country, but doesn’t tell him where, though he ultimately finds out she’s going to Zurich. Then when Stokes informs George an offshore account under an old alias Kathryn used recently received a lump sum payment of £7 million, he has no choice but to spy on his own wife.

Forcing Clarissa to help him, George discretely redirects a satellite to the exact coordinates his wife is going to be at while she is in Zurich. He sees that she meets with a Russian man and, using AI technology, is able to determine she isn’t selling, she’s looking to buy something from the man, but George runs out of time before he can get the full picture.

However, George’s actions backfire. He soon learns that while he had the satellite diverted, a Russian, Pavilchuk (Daniel Dow), who the agency was monitoring, escaped their surveillance; meaning he had a contact in the agency that knew this would happen. An agency higher up, Stieglitz (Brosnan), expects Pavilchuk is now heading to Russia and has obtained Severus, which the agency designed to covertly cause a nuclear reactor meltdown that could destabilize a government. George, for the first time, is rattled as he may have indirectly jeopardized thousands of innocent lives. The only way to stop it is to find the traitor and stop their plan in time.

Who is the traitor in Black Bag?

Clarissa tells Freddie what George did with the satellite, which sends Freddie into action, including calling an unknown individual and then meeting Kathryn upon her return from Zurich before she sees George. He fills her in and wants her help to fix it, but Kathryn says she needs a night to think.

The bond between George and Kathryn is too strong though, as the two promise to work together to stop Pavilchuk and find the traitor.

On the first part, Kathryn meets with a CIA contact to have them order a drone strike on Pavilchuk as he travels to Russia. We learn it was Stieglitz’s plan to get Severus to Pavilchuk, hoping he would use it to destabilize Russia and end the war (never specified, but presumably the one with Ukraine), ignoring the cost of innocent lives. But Kathryn and a successful drone strike put a stop to that.

Now it’s George’s turn, as he runs Stokes, Freddie, Clarissa and Zoe through a polygraph test to find out who is the liar. However, he’s not 100% sure, so he invites them all to dinner for one final reveal.

When everyone is there, Kathryn places a gun on the table (she is no longer a suspect), saying whoever doesn't answer George’s questions correctly will be shot. George reveals his theory that there were two plans involving Severus at the same time.

First, he knows Zoe and Freddie are sleeping together and collaborated on one of the plans. They were specifically trying to influence Kathryn and George so they would stop Stieglitz’s plan and save the innocent lives that would be at risk if Severus was used.

George then commends Clarissa for being able to manipulate the polygraph machine better than anyone he has ever seen, but he acknowledges that she had nothing to do with this situation.

That leaves Stokes. George reveals he was able to obtain pictures of Stokes in Myanmar, where the account he had claimed was set up by Kathryn was originally created, pointing to Stokes being the traitor. Stokes’ response is to grab the gun on the table and proclaim George has no evidence that will hold up. George then points out he’s been recording the whole proceedings, now including Stokes' confession. Furious, Stokes attempts to shoot George, but his gun is filled with blanks. Kathryn’s, however, isn’t, as she pulls it out of her purse and kills Stokes.

So George and Kathryn save the day and, as revealed in the final moments, get a nice bonus. Kathryn asks what happened with the £7 million that was in the account Stokes created. George says it is going to remain there, alluding that they are keeping it for themselves.

What does Black Bag mean?

Now that we’ve covered the key plot points, there is one other question viewers may have from the movie — what does Black Bag mean?

It appears the term is a catchall for the agency’s spies when dealing with sensitive information, likely because a black bag would be able to hide what was inside it.

Clarissa explains it best when George comes to ask for her help with the satellite. She says that whenever George, Kathryn, Freddie or any other spy wants to avoid revealing details (whether it’s about a mission or even something personal) they can simply say it’s black bag and that ends the conversation.

Black Bag is now playing exclusively in movie theaters.