Aaron Sorkin, the award-winning, dynamic writer behind The West Wing, The Social Network and The Newsroom has taken an unexpected subject for his directorial debut. Unexpected because Molly’s Game, despite being based on poker - a game full of suspense, unpredictability and skilled bluffing - lacks the depth and drama for which Sorkin’s sharp storytelling is notable.

This biographical tale is based on the true story of American “poker princess” Molly Bloom (Jessica Chastain), who ran a high stakes poker game for the super rich, powerful and famous and then a Russian Jewish mob, leading her to be indicted by the FBI. The film opens to Bloom recounting her life story to her lawyer (Idris Elba), which is delivered at a fast and furious pace, making it almost unfathomable. But instead of walking and talking in quick fire dialogue during one long take, in trademark Sorkin style, it is told in a dispassionate and over detailed voiceover.

Bloom, it transpires, was a champion skier with an Olympic future ahead of her until an accident put an end to that ambition. She moves from Colorado, away from her domineering therapist father (Kevin Costner), to California where she starts working as an assistant for a well connected man who organises weekly, underground games for A listers on the side. Highly intelligent and driven, she is soon the brains behind the operation and before long has quit working for him and is running her own games.

Bloom is steely, detached and is portrayed as quite a lonely, friendless figure. As the pressure of her expanding business leads to drug addiction, it is difficult to feel any empathy for her. Disappointingly, there is virtually no depiction of her struggle and this lack of character depth and exploration is one of the faults of Sorkin’s script. It never delves beyond superficiality. Bloom is described as the “goddess of magic” but there is no convincing sparkle about her and instead, Chastain’s performance verges on the bland.

The verbal spats between Elba and Chastain hold some interest and once she has persuaded him to take her case, Elba appears to develop a certain curiosity about his client. But her insistence that she will not reveal the names of some of her most famous players is source of frustration for him. Her name and reputation is all she has, she tells him.

For the uninitiated, the games themselves are fairly dull to follow but even for poker lovers and Sorkin fans, Molly’s Game might prove a challenge with its inflated running time of 140 minutes. Sadly too, for a film with a strong female protagonist, it feels like Sorkin has wasted the opportunity to create an engaging story.