Cool steps to star status

You think you know Rachel Whiteread's work - endless casts of beds, baths and floorboards - but seeing it again in the flesh stops you dead in your tracks. This show is exquisite. It isn't a retrospective so much as Whiteread's key moments: the first resin cast, the first mattress, the first bookshelves. The saturated jewel colours of her 1996 Tate Liverpool exhibition have been replaced by an emphasis on monochrome, with white plaster played off against black iron, plastic and urethane.

The former works much better than the latter. The pi?ce de r?sistance sits in the central rotunda: a white cast of an entire staircase, made earlier this year. It takes you a while to realise that this mindbending configuration of steps and doors is displayed lying on its side. Rising to the ceiling like an impregnable watchtower, it's the eerily monumental star of the show.

Less successful are the 99 black iron floor tiles that open the exhibition. Whiteread's work has always played off Sixties minimalism, but this take on Carl Andre's floor sculptures is weak and obvious - and is worsened by the intrusion of Joe Public's scruffy footprints all over it. As with the black bath and bookshelves, this density of darkness conceals all traces of the object from which it was cast - the very twist that gives her white works such ambiguous presence.

Despite this, major aesthetic swoons are virtually guaranteed elsewhere. In the east gallery, both the materials and their drained colours are spot on - almost edible: the concave and convex mattresses are like pale fudge, oozing out of their cast to leave a wafer-thin ridge, while the resin desk and chair standing next to them have the semi-opaque density of jelly. While we're talking synaesthesia, her work also seems to suck away noise - oppressively so. Each work has choked and smothered another object in order to be made, and this deathly process adds a psychological frisson to your sensuous rush.

Whiteread is rightly acclaimed as one of our best sculptors, and this show is chilly perfection for hot days ahead.

Until 5 August at the Serpentine Gallery Box office: 020 7402 6075.