At nine Mwangi opens the stall. He takes the tarpaulins off the crates and puts them under the counter. Next to him there is nothing to open.

Where the stall next door stood the ground is lighter. It is a clean rectangle, and at the four corners are the hollows left by the stall's feet. In one of the hollows there is water. It has not rained for three weeks.

Mwangi takes the onions out of the sacks and puts them in two crates, and with the back of his hand he clears the soil off the counter.

Mwangi looks down the aisle, to where the aisle turns and nothing more can be seen. Then he whistles. He always whistles the second half of the same song and never the first.

He unrolls the sheet from the pole. It is light blue, still with the folds from the shop, four white stripes dividing the cloth into equal rectangles. In one corner is the plastic tag. He hooks it to the eyelets, three on this side and three on the other, and when it is hooked it reaches a good metre beyond his pole. It is longer than the stall. Not that he bought it for that.

The boy with the cart goes by and asks him if he has room today. Mwangi says no.

At half past nine a man goes by who greets him, and Mwangi tells him before the other has asked anything.

"I'm keeping it for him, you know."

The man nods and moves on. He had said it yesterday too, out loud, in front of two people who were loading a cart.

His son comes with the water and asks if he should pull the sheets. Mwangi tells him no and tells him to stay at the stall.

The two women who used to buy from the other one arrive at ten. They stop at the boundary, where the ground changes colour, and they stay there, and they ask him what they used to ask the other one.

"Have you got the small tomatoes?"

"Today I have these, mwalimu."

He weighs, wraps, counts the change and lays it on the counter. One of the two pays with a banknote folded in four. The banknote is warm. Mwangi puts it in the box under the counter, and as he puts it he looks at the stall opposite, where there are two men who are looking at him.

At ten the aisle is full, with the cereal women shouting the prices from the far end, with the carts passing in the narrow space between the stalls, and over all of it the noise of the roof sheets heating up and moving by themselves.

He bought the sheet four months ago, at the depot behind the station, and he did not tell anyone. He kept it in the sack until this morning. After all a new sheet in a market is a thing that gets noticed.

Around eleven the cook from the food stand comes down the aisle with the bucket. She looks at the light rectangle, moves a step aside so as not to walk on it and says that Niyonzima's place has stayed clean. Then she goes on the way she always goes.

Mwangi pulls the sheet a little and leaves it there.

At the end of the aisle the market supervisor appears.

He comes up the aisle with the register open between his two hands. Under his arm he holds a closed umbrella. He stops at every stall, looks at the number painted on the pole, writes, moves to the next stall.

Mwangi pulls the sheet. The first pull takes it a hand's width beyond his pole. He raises his eyes. The market supervisor is at the sandal stall.

Second pull. The cloth comes out of the shop fold, stays swollen in the middle, because it has never been opened all the way. The market supervisor is at the egg stall, and the egg woman says something to him, and he does not lift his head from the sheet of paper.

Third pull. The sheet reaches over the first of the four hollows.

The market supervisor reaches the stall before his and does not stop. He says, to the paper, that a place empty for three days goes back on the list, and that someone two stalls further along has already asked for it yesterday. He says it while walking.

Mwangi does not answer. He takes the rope from the pole of the place next door, passes it through the eyelet and pulls, and the sheet stretches over the light ground until it covers all of it.

Then he bends down, takes a crate and drags it beyond the boundary. The wood on the untrodden ground makes a drier sound, higher than the one it makes on the aisle. He drags the second crate and puts it in line with the first.

He does not tell the market supervisor that the place is being kept. He says nothing.

The market supervisor reaches his number. He looks at the sheet, looks at the two crates on the covered ground, marks the register with the pencil and moves on. He says nothing. Now it is written.

Under the sheet the four hollows are full of loose soil. The colour is the colour of the rest of the aisle.

Under the light blue sheet the goods have taken the colour of the sheet. Mwangi moves the onions into the right hand crate and puts the price card on the pole of the place next door. Twenty shillings a bunch. A boy stops, asks if they are yesterday's, and buys them anyway. In any case at that hour the onions are bought by whoever passes.

The cook from the food stand comes back up with the empty bucket, and she comes on the new side, because now that side can be walked on. She slows at the level of the sheet.

"You're keeping it for him, then."

Mwangi wipes his hands on his trousers and does not answer. The cook goes on and does not turn round.

At the stall opposite the two men stop talking while he looks at them. Then they start again.

Mwangi gives the sheet another pull. It is half a pull, the cloth moves a little and comes back. He stays with his open hand on the cloth and looks down the aisle, to where the aisle turns.