By Peter Keough

Two cheers for monogamy in Steven Soderbergh’s Black Bag.

Black Bag, directed by Steven Soderbergh. At the AMC Boston Common, the AMC Causeway, the Kendall Square, the Coolidge Corner, and the suburbs.

Cate Blanchett, left, and Michael Fassbender in Black Bag. Photo: Claudette Barius / Focus Features

If nothing else, Steven Soderbergh is a master of slick technique. His new film, his second in less than a year, opens with a tracking shot reminiscent of the Goodfellas Copacabana interlude. It’s from the point of view of George Woodhouse (Michael Fassbender), a pillar of probity and lethal efficiency in the British Secret Service. He’s meeting with his superior, Philip Meacham (Gustaf Skarsgård), who informs him that one of their agents has been compromised and is suspected of trying to sell to an enemy entity a top secret, potentially apocalyptic program called Severus. Why not just call it “MacGuffin”?

Meacham gives George a list of those to be investigated, one of whom, George is somewhat dismayed to learn, is his devoted wife and redoubtable agency colleague Kathryn St. Jean (a dark-haired Cate Blanchett looking like Emma Peel from The Avengers). The others are Clarissa (Marisa Abela), whose specialty is satellite imagery; her boyfriend Freddie (Tom Burke), whose specialty one would guess is getting drunk and cheating on women; Zoe (former Miss Moneypenny Naomie Harris), an agency psychiatrist, who, given subsequent events, is clearly not doing a good job; and Zoe’s partner James (Regé-Jean Page), who specializes in being a callow asshole. Along with Pierce Brosnan, who shows up later as Stieglitz, the delightfully seedy and apoplectic head of the agency, they put in performances that should be remembered at the end of the year for best ensemble cast awards.

In a ploy straight out of Agatha Christie, George invites the four to dinner, explaining to Kathryn, his faith in her apparently unshaken, how he plans to accelerate the interrogation by plying them with a truth serum (shades of MKUltra). “Will there be a mess to clean up after?” she asks. “If we’re lucky,” he replies. They will not be disappointed, nor will it be the last time they have this exchange.

The unsuspecting suspects arrive at George and Kathryn’s London flat, which is swanky but gloomy because everything in the film seems to be shot through a murky, greenish filter that makes it look like it is taking place behind the mildewy glass of an untidy aquarium. It’s an oppressiveness not mitigated by David Holmes’s blowsy, percussion-heavy Ocean’s Eleven-like score, which adds to the aural murkiness of the Altmanesque, overlapping party banter. Tartly scripted by David Koepp, this cross-talk is studded with tantalizing, half heard non sequiturs, which, combined with the twisty, carefully contrived, red-herring-riddled plot, is reason enough for a second viewing. Take, for example, a stray comment from a guest about how the assassination of the Roman emperor Commodus led to 50 years of civil war. An extraneous detail one might think, but then one of Commodus’s imperial successors was named Severus.… And so on.

Under the influence of the facilitating drug, however, these pleasantries do not last, and the underlying rottenness of the guests’ relationships is revealed and a lot more dirt besides. But none that helps solve the mystery, and some of which, coupled with a movie ticket found in a wastebasket, adds a furrow or two of possible suspicion to George’s brow.

But who can tell what he is really thinking? George’s face is a mask, frozen into the knowing stoicism of an image on an ancient coin. If he shows any expression, it probably means matters have truly gotten out of hand. Even then, George exudes the subdued menace of Terence Stamp in Soderbergh’s 1999 masterpiece The Limey, though deceptively muted with a pair of George Smiley spectacles. Kathryn, too, is hard to read, but their scenes together evoke not the acrid hostility of the cynical agents in Mr. and Mrs. Smith (2005) or the soused spouses in Who’s Afraid of Virginia Woolf (1966) but the wry, tacit, unbreachable bond of Nick and Nora Charles in the Thin Man series.

Later, when the plots thicken and things look hairy, George tells Clarissa, whom he has extorted into breaking the rules to assist him in helping his wife, “If she’s in trouble I’d do anything to extricate her” (to which Clarissa replies, “That is so hot.”). And, as Kathryn exclaims at another key moment, “Don’t you ever fuck with our marriage again!”

But will their loyalty to each other endure? Will it prevail over the world’s treachery or, as one of their questionable co-workers suggests, might it prove a detriment rather than a strength in their profession? More than just a master of technique, Soderbergh, since his debut feature sex, lies and videotape (1989), has repeatedly and incisively explored the themes of fidelity and integrity, duplicity and betrayal. Now, at a time when every social contract looks to be crumbling, he ponders whether the most basic one can survive.

Peter Keough writes about film and other topics and has contributed to numerous publications. He had been the film editor of the Boston Phoenix from 1989 to its demise in 2013 and has edited three books on film, most recently For Kids of All Ages: The National Society of Film Critics on Children’s Movies (Rowman & Littlefield, 2019).