Part gritty prison drama, part hard-boiled gangster thriller and part crafty heist caper, this Australian crime movie switches genres with ease, pinching as it goes from a string of classic crime films including A Prophet and Heat.

Brenton Thwaites, previously seen as a fairy-tale prince in Maleficent, is convincingly wet-behind-the-ears as the story’s callow protagonist, 19-year-old young offender JR. Sent to prison for six months for a minor crime, he looks to be easy prey until he is taken under the wing of ruthless career criminal Brendan Lynch, played by a dangerously charismatic Ewan McGregor.

The protection comes at a price, of course, and the payback embroils JR in a bold jailbreak and an even bolder gold-bullion robbery from a desert mine. Yet even riskier is getting mixed up with the beautiful Tasha, the disaffected girlfriend of the powerful gangster bankrolling the heist, played by Swedish actress Alicia Vikander, currently on a roll following standout performances in Testament of Youth, Ex Machina and her Oscar-winning turn in The Danish Girl.

Along the way, the plot veers off in some far-fetched directions, and how the story eventually pans out is only minimally credible. But first-time writer-director Julius Avery keeps things on track and his brisk handling ensures that the switchback narrative is always gripping. At times, he does rather overdo the symbolism, with McGregor’s chess-playing Brendan pressing JR in one scene to decide which type of ape he is descended from – aggressive chimpanzee or loving bonobo.

Still, for all its flaws, Son of a Gun remains a solidly entertaining crime film and an impressive directorial debut.

Certificate 15. Runtime 109 mins.  Director Julius Avery

Son of Gun is shownig on Sky Movies Premiere tonight at 10pm.