The career revival Keanu Reeves managed via the two “John Wick” movies comes to an abrupt halt with “Siberia,” a tale of chicanery in the illicit Russian diamond trade so murky and drab that one might have expected it to star Nicolas Cage. It also represents the sophomore jinx syndrome for director Matthew Ross, whose “Frank and Lola” was an auspicious debut, as well as a “what was he thinking?” query aimed at Scott B. Smith, who twenty years ago adapted his novel “A Simple Plan” for the screen with striking results.

Reeves, who is also one of the producers, stars as Lucas Hill, who arrives in St. Petersburg to complete a deal to sell rare blue diamonds to mobster Boris Volkov (Pasha D. Lychnikoff). Unfortunately his partner Pytor has disappeared, forcing Hill to travel to a small Siberian mining town to try to get the stones himself.

There he runs afoul of some of the loutish locals, but is rescued by Katya (Ana Ularu), a bartender who not only salves his wounds but falls into bed with him. He responds with as much eagerness as Reeves, looking somber and pained throughout, can muster—despite the fact that he’s married to Gabby (Molly Ringwald, who literally phones in most of her cameo on Skype).

There are further complications as Katya’s protective brother Ivan (Dmitry Chepovetsky) enters the scene to ensure that his sister is not led astray by a scoundrel. In one episode, Hill is not so gently encouraged to join Katya’s relatives in a wolf hunt, where he—not unexpectedly—demonstrates his virility. (He is, we are given to understand, not the sad-faced wreck he at first appears, but a man with hidden resources—he can quickly go physical when required, and speaks Russian, though he hides the fact to outwit opponents.)

But there is still the business with Volkov to complete, and with Pytor’s continued absence Lucas grows increasingly concerned about whether he will be able to deliver, and he is compelled to agree to reworked payment terms to make up for the delay. The mobster’s attitude toward women is also a problem, especially after he gets an eyeful of Katya and makes some unwanted suggestions. Hill’s concern about where matters are headed leads him to enlist the help of a big-time South African dealer (James Gracie), who is interested in acquiring the diamonds himself; menacing government agents, led by a threatening fellow named Polozin (Eugene Lipinski), also pop up to muddy the waters.

“Siberia” rouses itself for a gun battle in the snow to end things, but for most of its overextended running-time it’s a slow, tedious trek through pseudo-Russian territory (most of it was shot in Winnipeg, with some St, Petersburg exteriors added to lend a tinge of authenticity) with the perpetually morose Reeves as an uncharismatic travelling companion. Whatever promise he might have perceived in the script certainly has not been realized in the execution.

Major blame for that rests with Ross, who brought a coiled tension to “Frank and Lola” that’s sadly lacking here; straining for a nourish sense of foreboding, the film only manages to be dankly tedious. The laxity is accentuated by Eric Koretz’s monotone cinematography and Louise Ford’s lethargic editing.

At one point when Hill asks Volkov for more time to deliver the stones, the mobster replies that patience is like oxygen in a sealed room—eventually it runs out. Most viewers of “Siberia” will have exhausted theirs long before the final credits roll.