Chapter 18: An umbrella stays shut through the heaviest rain of October

Zelda Ruskin's umbrella stall fills the narrow arch between the café and the Flower Hall. A brass stand holds the umbrellas for sale, fanned out like a winning hand of cards. Behind it, on a rail of hooks, hang the mended ones waiting for their owners, each with a paper tag and a name in pencil.

Open any umbrella on that rail, as you do now, and you will find the answer to the red thread. Around one rib, close to the top, Zelda ties a tiny knot of red cotton before a mended umbrella goes back on its hook. Her stock for sale never carries one.

On a rainy day half the black umbrellas in the market look alike. The knot means she never sells a customer's umbrella by mistake, and always knows her own work when it comes back. “Forty years,” she tells you, “and not one mix-up.” On the second Saturday of October the knot is about to earn its keep.

Una Thistle's grandmother's umbrella is the finest thing on the rail: black silk, a silver handle shaped like a duck's head, a new rib put in on Tuesday. At a quarter past ten Zelda checks it, and the knot is there.

At eleven Una comes to collect it, opens it under the arch, and goes pale. The duck's head is painted tin. There is no red knot. Somebody has swapped it.

Una tells you the umbrella has been coming to this market longer than she has. Her grandmother carried it across the square on her wedding day, in a thunderstorm, and had the duck's head fixed back on at this same arch, by Zelda's mother, the week after.

The rain began at twenty to eleven, a real downpour that sounded on the glass roof like a drum roll before a penalty. You were in the café with Inspector Elena Dorn when it started, and you watched the whole square turn grey in a minute.

At eight minutes to eleven Pim rang the rain bell, two short strokes, the old signal that the roof over the Flower Hall is leaking again. Every stallholder at that end of the market knows it the way a crowd knows the referee's whistle.

The rain bell is one of Pim's oldest jobs. In a wet October it rings three or four times a week, and the stallholders say they will miss it more than the big bell, because it always meant a few minutes of everyone helping everyone.

Zelda ran to help the flower seller drag the tulip buckets out from under the drip. She was back at four minutes to eleven. It was the only time all morning that the rail stood alone.

The copy hangs where the silver umbrella hung. Dorn hands it to you. You open it and run a finger along the inside of the silk. Bone dry. Every umbrella that has come in from the square since twenty to eleven is streaming, and the floor under Zelda's stand is one long puddle.

Three customers stood at the stall in the minutes before the rain bell. Ross Yardley, a café regular, had been in the market since nine, empty-handed, and wandered over at a quarter to eleven to buy a cheap umbrella for getting home.

Tessa Vickery ran in from the square at ten to eleven in a yellow coat, shook out her open, dripping umbrella and stood it in Zelda's stand. You can still see it there, a pool spreading under its tip.

Saul Webb came in at a quarter to eleven, soaked to the shoulders, with water running off his hat brim and a furled umbrella under his arm. Zelda noticed, because she offered him a towel, and he said no.

Now you ask them, one at a time, while Dorn stands at the rail and says nothing. Ross says he was at the café counter, paying, when the rain bell rang, and Mrs. Odile Fenn agrees: he was grumbling because she had given him his change in small coins, and she made him count every one in front of her, to teach him.

Tessa says she ran with Zelda to the leak, and Zelda remembers the young woman in the yellow coat taking the other handle of the heaviest bucket. Saul says he stayed under the arch the whole time, out of the rain. Nobody stood with him.

He is still under the arch now, at a few minutes past eleven, watching the rain come down in sheets on the square. The furled umbrella is still under his arm. He has not opened it once.

When you offer him a towel of your own, he shakes his head and tightens his elbow on the umbrella, the way a rugby player tucks the ball in before a tackle.

You go and stand exactly where Saul says he stood. From there the rail is an arm's length away, and the café window, steamed white from top to bottom, cannot see you at all. It is the best hiding place in the market, if you are playing hide-and-seek with the whole market.

Dorn asks Zelda one more question. Could anyone have lifted the umbrella off its hook while she was standing at the stall? Zelda snorts. “Not past me. I've had my eye on that duck since Tuesday. Nobody touches my rail while I'm at it.”

Dorn turns her back to the arch and lowers her voice. This is a list she learned from an old sergeant in the Fish Hall, she says, back when the café still had gas lamps and Mrs. Fenn's mother poured the tea.

Check what is wet and what is dry. Rain marks everything it touches, so anything that stayed dry was kept out of it on purpose.

Check the minutes when nobody was watching. A theft needs a gap, and the gap is usually shorter than people think.

Check each person against that gap, with a witness who had no reason to lie.

Check what people carry and do not use. A tool nobody uses at the one moment it was made for is not being carried as a tool.

You have everything now: a dry copy, a four-minute gap, three customers, and one umbrella that has not been opened. Before you read on, try to put two of those together.

First: The first way, by the umbrella that stayed dry

Start with the copy. It hung on the rail bone dry inside, in the middle of a downpour, so it was never opened in the rain. It came into the market furled and kept dry on purpose, because a wet copy hanging among dry, mended umbrellas would have given the game away at once.

Tessa's umbrella came in open and dripping, so hers is not the copy. Ross brought nothing at all into the market; he came to the stall to buy an umbrella.

Saul walked in from the square through a downpour with his umbrella under his arm, letting his shoulders soak and turning down a towel rather than open it. Nobody does that with an umbrella he means to use. He was keeping it dry for the rail.

And now, with the real one under his arm, he stands in the arch waiting for the rain to stop, because a silver duck's head is the one umbrella in the market that everyone would recognise the moment it opened.

Second: The second way, by the four minutes of the rain bell

Now forget wet and dry and use the clock. The silver umbrella was on its hook at a quarter past ten, and Zelda never left the rail except from eight minutes to eleven until four minutes to eleven, when the rain bell sent her to the leak.

The swap had to happen inside those four minutes, like a substitution made while the referee is looking the other way.

Ross was at the café till with Mrs. Fenn, counting small coins. Tessa was at the other end of a tulip bucket with Zelda herself. Only Saul says he stayed by the rail, in the one spot the café cannot see, and nobody stood with him. The clock and the rain point at the same man.

Dorn asks Saul for his umbrella, very politely. Under the arch, with half the café crowding the doorway, she opens it. Black silk, a silver duck's head, and close to the top, around one rib, a tiny knot of red cotton.

Saul does not argue. He had admired the umbrella on Tuesday, when Una brought it in, and he had spent three days hunting for a cheap one with a duck's head that would pass at a glance. Una hugs Zelda and then, for good measure, hugs Pim, who goes as red as the thread.

Zelda ties a second knot on the silver umbrella before she hands it over, a little bigger than the first. “For luck,” she says. “And so that I remember this one when I'm too old to hold a needle and tell stories about the market instead.”

Remember: in the rain, the most suspicious umbrella in the market is the one that stays shut.

As the rain eases and you cross the Flower Hall, you pass the pumpkin stall, where a tall figure in a long scarf is buying the three biggest pumpkins on the pile and asking for them to be kept under a sack until next Saturday. The buyer pays with a little book of old green vouchers and will not give a name. Who pays for three giant pumpkins in old green vouchers and refuses to say who they are?