The story of Molly Bloom (a towering performance from Jessica Chastain, one of her best) is an extraordinary one. Over the course of 12 years she goes from being a potential Olympic skier protégée (undone by a particularly painful accident) to running a series of underground high-stakes poker games to being on trial in a mob case. The film explores Bloom's journey to this point whilst also delving into the legal wrangling that follows the collapse of her house of cards.

Molly's Game is a hoot, a rollercoaster ride with a dense script of snappy one-liners, fascinating anecdotes and weighty political arguments. It is big, bulky, and, for the most part, runs at a fabulous pace. Aaron Sorkin has form here as the writer behind such high-brow hits as The Social Network, Moneyball, and A Few Good Men. Whilst Molly's Game follows in the footsteps of several of these films, as an improbable yet true story of American excellence, it represents a first for Sorkin: he not only writes the screenplay but steps behind the camera to direct. The film doesn't have the visual panache of other Sorkin-scripted films and it at times creaks under the weight of its mighty script. Certainly when it finally slows down it loses some of its initial lustre, with one scene in particular feeling strangely slow and out of place. But the film shows that Sorkin is a very fine director indeed as well as being an iconic screenwriter.

One element that doesn't let him down is his casting. There are fun bit parts for Michael Cera and Chris O'Dowd and chewier material for Kevin Costner and Idris Elba. Costner plays the same father figure he's played for the past fifteen years and is fine in the role, sharing a spiky chemistry with Chastain. Elba is as good as ever here, a funny counterweight to Bloom, whilst also proving an effective sparring partner for some of the film's best scenes.

But this is Chastain's film and she is a dominating presence here. She devours the text and shapes Bloom into an almost likeable character, without forsaking what makes her so fascinating. An extraordinary story like this needs an engaging centre and that is what Chastain gives this film.

At times Molly's Game could be just as effective as a radio play, heavily relying upon voiceover and scenes of dense speeches. But when the script is this meaty and the performances are this strong, particularly from Elba and Chastain, you can forgive the film for its somewhat clunky nature. There is a lot of fun to be had and you will end up rooting for Bloom to win the day. Oh, and you don't need to know anything about poker to enjoy Molly's Game: it is one suitable for all.