Hill of Doors, By Robin Robertson. Picador, £9.99

Robin Robertson's fifth collection deepens and widens his characteristic territory: one that has become increasingly articulated, yet also more mysterious, from book to book. His profound debt to ballad tradition makes for story-telling poetry, often very beautiful and nearly always concerned with cruelty.

Hill of Doors revisits the classical myth and North Country legends that have been among Robertson's preoccupations since his 1997 debut, A Painted Field. Now, though, less effort is expended on integrating myth with contemporary life. Instead, his versions of the Greek poet Nonnus and passages after Ovid are kept in their original settings. The effect is of a brutal estrangement from the chattering contemporary world: a refusal to dissolve the shocking force of archetype.

Such gathering austerity is of a piece with the mid-career development of a major poet, and it's the opposite of arid. "Wire", an extended sequence of tercets, riffs on the desert spaces of the southern US "Frontera". This "no-man's-land" is busy with "human traces, ghosts", snakes, eagles and coyote, transformed into trickster outlaws. The notorious whirlpool of "Corryvreckan" is described first from sea-level, "the sea's so high it's climbing over itself", then "Seen from above, the tidal race is a long army moving fast", in a poem whose moiling participles "climb over themselves" until the astonishing closing statement: "The opened body of water that today we rode across." The image of the poet as adventurer is a good fit for Robertson, who makes us believe in a world vivid with symbols that it is his job is to broach or master.

This collection includes two stand-out poems. "Under Beinn Ruadhainn" is, like the earlier "At Roane Head", a tale to set your hair on end. In one stunning dream image, the local loch burns, "so full of bairns/ they bobbed to the surface/ with their hair on fire". The book opens with "Annunciation", a brilliantly poised meditation on that moment, and on the paradox of incarnation. Robertson remains an unequalled guide among the shamanistic roots of poetry.