Halfway through the second part of Rona Munro's trilogy, there is a banquet sequence. The cast chant and demand 'meat, meat, meat’: yet meat is absent from this episode, with too much gristle to chew on.

Munro charts King James' transition from gauche child (represented by a puppet) to assertive, decision-making adult in spite of opposition from all sides, particularly the condescending Livingston, Earl and Keeper of Edinburgh Castle (a braying Gordon Kennedy). Rather than preserve the historical period, the production updates the action and approaches the past as a melodramatic struggle for supremacy.

The modernisation feels a little facile: some perfunctory dialogue turns this fascinating story of power plays into something approximating parody, with big explosions and blockbuster sound effects bombarding the senses. The huge claymore sword stuck through the mist-covered set becomes a symbol of the problems of the production, which abandons nuance for the broad, expansive stroke.

Nevertheless, the cast are consistently impressive. There's great supporting work from an understated Rona Morison as James' sister, and Andrew Rothney as James is a charismatic lead. Unfortunately, the 'bromance' between James and his slowly unravelling best friend William Douglas, played with swagger and little else by Mark Rowley, is given too much attention and time, and the tone throughout is overwrought. Sadly, not even the wonderful Blythe Duff as the incarcerated Isabella Stewart – with battery acid in her veins, and some of the best lines – can redeem this. Too much fat for seconds.

James II: until 21 Aug (not 14 & 15, 18 & 19). All performances at Festival Theatre, 473 2000, times vary, £15– £35.