Who can you trust in a world of spies when it is so easy to cheat because of the possibility of a “Black Bag” assignment? That assignment is often to hunt a spy because “It takes a spy to hunt a spy,” but what if that spy is one’s spouse?

This isn’t another “Mr. and Mrs. Smith,” because under the direction and atmospheric cinematography of Steven Soderbergh, the smart writing of David Kopek (“Mission: Impossible,” 1996 and “Indiana Jones: The Dial of Destiny,” 2023) and a rushing soundtrack, this is a thriller that exists in what could be a real world.

When we first meet George Woodhouse (Michael Fassbender), he’s walking through the streets of London, into a club. We mostly see the back of his neck. He is wearing a suit jacket over a (shades of the 1960s Illya Kuryakin from “The Man from UNCLE”) a dark turtleneck. Into a smoky nightclub he goes to meet Philip Meacham (Gustaf Skarsgård), a bald man who sits between two much younger blonde beauties, but this is as close as we get to the James Bond sleek and hedonistic image of the British Secret Service.

There is, Meacham informed George, a mole, a spy who is betraying their agency and the possible people has been narrowed down, but one of them includes George’s wife, Kathryn St. Jean (Cate Blanchett). At the center of this betrayal is a project that the Russians want and the British have. There are some moral ambiguities attached to the project dealing with nuclear warfare.

George is a homey type. He does the cooking and when we next see him, he’s expertly chopping onions and simmering a masala which he warns his wife not to partake in because he’s included a special ingredient, a psychoactive drug designed to make people tell the truth. She’s calmly delighted to learn there will “be a mess to clean up.”

George is infamous not only for something that happened in Syria in 2012, but also for how he torched his father’s marriage and career all at once. As an explanation, he says he hates liars. That’s a curious thing when half of one’s adult life is in a “black bag,” meaning a secret operation that can’t be divulged to the listener.

The guests have decided that although they can’t refuse an invitation from George who is management in this agency, they can be prepared. Even if they feel like their going to their parents’ house, there is a whiff of danger. Freddie (Tom Burke) arrives late even though he was the one who first suggested they meet for a bit of wine. Freddie is having an affair with Clarissa (Marisa Abela) while Zoe (Naomie Harris), the Agency shrink, has been hooking up with James (Regé-Jean Page). Fortified with liquor, they arrive knowing only that one must praise George’s culinary skills.

At the table, they will play an uncomfortable game of truths and there will be a bit of blood shed. Romance can be a nasty thing amongst spies. Yet upstairs alone in their spacious living quarters, George tells his wife the dinner was “the rock” and not he will “just watch the ripples.”

Although she knows he hates liars, Kathryn asks, “Would you like for me?” George admits he would and adds, “But never to you.” For her part, Kathryn says she would only lie to him if she had to.

One of the ripples catches up with Meacham who dies and this is only Friday.

On Monday, Kathryn meets with therapist Zoe with the “aroma of hostility” and we learn she is on drugs to control her nightmares, but just enough so that Zoe can’t report. Kathryn reveals, “My devotion to my marriage is my gaping weakness.”  Yet she worries about money because she notes, “I will not end up like my mother.”

George meets up with James who notes that a cover name is being used and a large lump sum has been added. There’s a connection to Kathryn.

Tuesday, George and Kathryn go to see a film, “Dark Windows” (a real 2023 Norwegian film) which George believes Kathryn has already seen.

On Wednesday, Kathryn is off on her “black bag” mission, but George already knows she’s going to Zurich, having accessed her work calendar on her computer at work while she was in a closed meeting headed by Arthur Stieglitz (Pierce Brosnan).

By Thursday, George has convinced Clarissa to help him spy on Kathryn by re-directing spy technology for a few minutes. Yet those few minutes will cause dominoes to tumble.

I’ve seen other reviewers compare “Black Bag” to “Mr. & Mrs. Smith,” but I don’t think either works wells.

The 2005 “Mr. & Mrs. Smith” which spawned the ill-fated romance between stars Brad Pitt and Angelina Jolie was an action comedy. Both of the Smiths are assassins belonging to competing agencies who are assigned to kill each other but they don’t know that the other is an assassin and being an assassin is different from being a spy.

The Amazon Prime TV series “Mr. & Mrs. Smith” feature Donald Glover and Maya Erskine as two strangers paired up and  live undercover as a married couple. Their names, John and Jane Smith, are their agency aliases. My husband and I watched Season 1 and spent too much time yelling at the screen. There were gaps in logic. While the writers are quick to note that Glover’s character might be one of a few Black men in the room and thus he decides he’d be more inconspicuous as a wait staff, the writers ignored how a Black-East Asian couple would attract attention and even animosity from both the Asian American community and the Black/African American community. That kind of racism is real.

In “Black Bag,” we have a married couple who are both successful in their chosen trade and working for the same agency. They have skills and they have are used to working as a team. Their familiarity with each other makes them a team and yet makes them vulnerable to attack.

“Black Bag” is a sensual, seamless look at spies and betrayal and the possibility that love can exist. The cast fill their characters with nuanced ticks that tease us as we guess who is telling lies and who is not and what lies are necessary in every day life. The casting of Brosnan is, of course, clever. We can hope that spies do survive and keep tangling in world affairs, even if they aren’t off on high casualty adventures.  Now knowing who the mole is, we can’t wait to see the film again and see how and when the clues are dropped.

“Black Bag” will be released by Focus Features in the US on 14 March 2025.