At the end of Henry V, which completed the first part of the history marathon that the RSC is running in rep at the Roundhouse, the Chorus casually remarked that the all-conquering king's son would lose France and England would bleed, “which oft our stage hath shown”. Well, yes.

Michael Boyd's vivid, vital production of the Henry VI trilogy doesn't just show England becoming an abattoir: it helps you to understand why Shakespeare the actor, whose first plays these may have been, so rapidly became a popular success and his company's most trusted dramatist.

The Henry IV plays, which Shakespeare wrote later in the 1590s, are far more sophisticated, but Henry VI is the Elizabethan counterpart of Doctor Who or some other adventure series. It's packed with colourful incident: plots and counterplots, deceit and betrayal, gory violence and escalating atrocities, sinister wizards and the malignant witch we now revere as St Joan. And, thanks to Boyd's inventiveness and a company happy to climb ropes or be lowered from high above, the revival has an imaginative immediacy no television programme could match.

Take the scene in which Geoffrey Freshwater's slimy Cardinal Beaufort dies, wailing hideously and trailing his scarlet bed-linen, as the mottled ghost of his murdered enemy, Richard Cordery's Duke of Gloucester, hoists him to the flies. Or the Jack Cade rebellion, with John Mackay spinning like a psychotic Nureyev at the head of a crew that includes beggars, spooks, cripples, a ferocious butcher, one man without a head and another who has borrowed his from a blend of lizard and parrot. It's anarchic. It's demented. It's both.

Both these events occur in Part Two, the liveliest play in a trilogy each of whose sections can, but preferably shouldn't, be seen alone. Part One is much preoccupied with the French wars waged by Keith Bartlett's tough, scrawny Talbot, Part Three with the intricate ascent of the Yorkists. But neither there nor anywhere did I (or, I felt, anyone else in a packed house) tire of a day that lasted more than 12 hours. True, the nobles spend a lot of time badmouthing each other - vile Somerset, proud Suffolk - yet the acting is always forceful and gripping.

I can't imagine a Queen Margaret who glitters with more menacing glee than Katy Stephens, or a better Henry VI than Chuk Iwuji, who begins by catching the boyish naivety, ends by acquiring great spiritual gravity and, throughout, gives the trilogy a point that crosses the centuries from one anxious Elizabethan era to another. It's about the ineffectiveness of love, charity and the spirit of reconciliation in a bad world: indeed, one here being dragged to its abyss by Jonathan Slinger's mocking, bitter, baleful Crookback. But more of him when I review Richard III tomorrow.

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