Aaron Sorkin has found his muse in Jessica Chastain, who is certainly up to the task of bringing the signature Sorkin hyperarticulate dialogue to life as the star of “Molly’s Game.” When she’s not trading verbose quips with the equally formidable Idris Elba, she is narrating the film, and in her capable hands a complex and dense story is made clear and exciting, despite a somewhat bloated run time.

As real-life character Molly Bloom, Chastain portrays a person bred for success by her demanding father (Kevin Costner) and, when her Olympic skiing career is derailed by an injury, she turns her prodigious abilities to excel in any field to a completely unexpected one. A low-paying job in the office of a real estate mogul changes her life forever when she starts running his weekly, secret, high-stakes poker game.

Molly quickly learns more than her boss about his game and his high-profile clients and, when the timing is right, she poaches the whole affair and makes it her own. This whole turn of events is fun and exciting to witness, as Molly goes from Googling poker terminology to managing a game with a $50,000 buy-in.

This film and Molly’s character are created entirely from action: Molly has no life beyond what she does. She has no love interest, no personal life, nothing like that is on display in this film. Every bit of her character is external, yet Chastain creates a character from this. She is a fascinating portrait of almost pure ambition that is rare to see in a female role. Aside from her wardrobe, however, she doesn’t exist much as a male or a female; she is a brain determined to make money, and a voice telling us how she did it.

Depending on your taste, this is a shortcoming, or it’s just a facet of the film. Is it a statement that to be this driven, everything else must fall away? Or is this just Sorkin’s particular way of telling his story? If creative writing classes teach you “show, not tell,” Sorkin was absent that day. All Molly does is tell and tell and tell. But it’s a fascinating story she’s telling.

The cast of poker players rounds out the film nicely. Michael Cera plays a movie star Molly simply refers to as Player X, and Cera makes him matter-of-factly despicable. His desire to win is motivated by his need to make other people lose, and his glee is perfectly underplayed. Cera brings a lot to his character beyond his default nerd setting, and it’s a weirdly powerful role for him.

“Stranger Things” fans will delight in the presence of Joe Keery as a trust-funded gambler, and Chris O’Dowd gives us some of the film’s rare moments of human emotion, even if it isn’t very noble. This film is so devoid of human feeling that even the gorgeous women paid to hang out aren’t paid for anything sexual. This is a purely cerebral movie, like an action film. Except the action isn’t car chases or shootouts, it’s lost fortunes and courtroom reveals.

When Molly gets nabbed by the Feds, her reluctant lawyer (Idris Elba) tries to figure out why she will go so far as to name names in a tell-all book she just published, but won’t name others to keep herself out of prison. With the Russian mob involved, the stakes are pretty high.

I do think the film could have been shorter, but with Aaron Sorkin directing an Aaron Sorkin script, I can see how cutting anything was unlikely. A fascinating story brought to life by a spellbinding star, “Molly’s Game” is Chastain’s film, and a gripping journey through a rarefied world.

“Molly’s Game” is currently available to rent.