No one weaves such tangled webs of lies, corruption and deceit as David Mamet. Into his world of cutthroats, card sharks and magicians, he has, in his new release Redbelt, mixed in something even more surprising.

Plot twists, shady settings and mysterious characters crop up often in the Mamet oeuvre, and they do so again in Redbelt. But instead of taking place in a sleazy back room or grimy pawnshop, they mostly unfold at the South­side Ju-Jitsu academy. It’s there that Mamet introduces his new favored topic, a Brazilian form of mixed martial arts.

Mamet’s latest personal diversion does not translate well onto screen, however, as it holds more awkward, out-of-place moments than any previous Mamet work. Nevertheless, the prolific playwright, screenwriter and director creates an erratically compelling story of subterfuge, dedication and, as always, misdirection, be­fore crumbling almost completely in third act, subpar, sports-film hokum.

Magnificent British actor Chiwetel Ejiofor plays Mike Terry, owner and head instructor at Southside. One evening, he serendipitously uses his expert ju-jitsu skills in a bar to rescue Chet Frank (Tim Allen), a slumming movie star who then superficially befriends Mike, drawing him and his wife Sondra (Alice Braga) into a privileged inner circle.

Once surrounded by what seems a rarefied atmosphere, Mike suddenly finds himself betrayed and beholden to shady interests. Meanwhile, Mamet also draws one of his seemingly innocuous subplots, one involving Joe (Max Martini), a police officer, and Laura (Emily Mortimer), a high-strung attorney.

The third act signals the crumbling of Mamet’s intricate plotting, as Mike, betraying his personal code against competition, begrudgingly enters a big-time, big-money martial arts tournament. There, the threads of the story unravel, ending in a superficial showdown that signals lesser-Mamet.

Mamet mostly avoids his trademark staccato dialogue, turning instead to more fitting, naturalistic conversations. Mamet has never developed a visual style but has become skilled enough to keep his shaggy dog stories interesting. And although Redbelt qualifies as passable entertainment, it also feels like a subpar work from its creator.

Red Belt

** 1/2

Rated R, 99 minutes.
Opens today.