Cildo Meireles, Tate Modern, London

Some kind of altercation is going on at the entrance to the gallery which houses an installation called Volatile. The gallery attendant, perched on a high stool like a budgie on a perch, is telling an irascible young man with wild hair what he has to do before he can see the art next door. Pull on paper mask. Remove shoes. Replace with Wellington boots.

We go through the door together, and do the necessary. In the ante-room, one of my wellies is ridiculously roomy, and the other one was made for an eight-year-old. Oh, well. I pull on a mask, then we heave back the door and go in.

It's fuggy and dark, and my feet are sinking into something deep and clingy. I foot-slog my way through, then turn a corner, into an area where there's a light coming from a candle in the middle of the floor. It feels like a shrine in here, but what is this weird stuff I'm sinking into?

"Is it flour?" I ask my young friend.

"It's talcum powder," he says. "Flour feels coarser than this." He tweaks some up between thumb and finger, sniffs. Nods. Talc it is.

This exhibition by veteran Brazilian conceptual artist Cildo Meireles consists of curiously immersive engagements with objects as bizarre as the kinds of things I have just described. Another installation comprises a room full of red objects. Next door, a small bottle lying on its side on the floor seems to be spilling gallons of blood, far too much liquid for such a tiny receptacle; go still further, and you encounter a sink on the tilt which appears to be hovering. As you approach it, you see that a tap is running with red liquid.

An investigation into the paradoxical nature of objects is how Meireles has described his weirdly delightful approach to art-making. We're told it's conceptual art, and this may well be so if you could get a handle on the ideas that these pieces are trying to embody.

In fact, you could reduce each of these works to a bald summary of its meaning, and much of it would be to do with parables of political repression. But that would be to limit the serendipitous pleasures of this show, which keeps wrong-footing us, sending us in one direction, and then flinging us elsewhere.

And all this paradoxical stuff is awfully messy, too. I spot no fewer than three Tate attendants wielding dustpans and brushes, clearing up all the stuff that's spilling beyond the edges – bits of glass, clock hands and, oh yes, that filthy talcum powder, which, even now, is sticking to my typing fingers.

To 11 January (020-7887 8888)