When it comes to sagas, they don’t come much more epic than Game Of Thrones. The string of books in George RR Martin’s series, A Song Of Ice And Fire, spawned a phenomenally successful TV series. Now, the fictional continent of Westeros is brought to Stratford-upon-Avon in the shape of the Royal Shakespeare Company’s latest production, Game Of Thrones: The Mad King, an extraordinarily enthralling tale of the struggle for power and all that goes with it. Family loyalty and friendships are tested, allegiances are made and broken, brutal war breaks out - this is a story that exposes human nature at its dark, ruthless and gory worst.

Adapted by Duncan Macmillan and directed by Dominic Cooke, The Mad King imagines the events which preceded A Song Of Ice And Fire. Aerys II Targaryen (Michael Shaeffer) is the monarch of the title, in the grip of full-on insanity. His reign is characterised by irrational and brutal decisions which threaten the stability of the realm. His son, Rhaegar Targaryen (Noah Ritter), begins to imagine the unthinkable - rebellion, in order to unseat his deranged father. Into the mix are thrown rival powers, including House Stark and House Baratheon, united somewhat uneasily by the betrothal of Lord Robert Baratheon (Callum Woodhouse) to Lyanna Stark (Harmony Rose-Bremner). And thus the action unfolds.

This RSC production feels like a once-in-a-lifetime event. Rarely can such a wealth of drama, skill, special effects and ambitious stagecraft come together to create a spectacle like this. Game Of Thrones aficionados will delight in the intricate nuances of the plot and the complex relationships between the characters, but those who are not so well-versed in the ways of Westeros are equally sure to be swept away by the entrancing story as it unfurls onstage.

Visually, The Mad King is captivating. The cross-formation stage brings the audience close to the action, and the set is constantly shifting, at one moment invoking the sumptuous setting of a celebratory ball, the next the stark reality of war and man’s brutality to man. Individual actors move with split-second precision, their movements at times almost balletic, and the use of beautifully crafted puppets to bring to life horses and dragons is simply magical.

The energy onstage is unfailingly electric and the performances are compelling. As the sets constantly shift, so does the mood of the piece. When the numbers onstage are large, the ensemble move like a well-oiled machine and the level of drama is high. Equally effective, though, are the more restrained scenes, some touching, some sinister and dark, but to see drama of this quality cannot fail to fascinate.

The ambition of those who conceived the idea and the vision for The Mad King, together with the skill and talent of those who are bringing it to life, can only be admired. This is a truly remarkable piece of theatre, one that is sure to live long in the memory of every single person who is lucky enough to get a ticket.

Reviewed by Rachel Smith at the RSC, Stratford-upon-Avon on Wednesday 5 August. Game of Thrones: The Mad King continues to show at the venue until Saturday 5 September