The Flanders Panel

The sigh of relief that escaped her must have been audible to Munoz, who interrupted his explanations to ask if she was all right. He was terribly sorry to phone her so late but he felt he was justified in waking her. He himself was quite excited about it; that’s why he’d taken the liberty of calling. What? Yes, exactly. Five minutes ago the problem suddenly… Hello? Was she still there? He was telling her that it was now possible to ascertain, absolutely, which piece had taken the knight.

VII Who Killed the Knight?

The white pieces and the black pieces seemed to represent Manichean divisions between light and dark, good and evil, in the very spirit of man himself.

G. Kasparov

“I couldn’t sleep for thinking about it… I suddenly realised that what I was analysing was the only possible move.” Munoz put his pocket chess set down on the table, smoothed out his original sketch, now crumpled and heavily annotated, and placed it beside the set. “Even then, I couldn’t believe it. It took me an hour to go over it all again, from start to finish.”

They were in an all-night bar-cum-supermarket, sitting by a large window that gave them a clear view of the broad, empty avenue. There was hardly anyone there, a few actors from a nearby theatre and half a dozen night birds, male and female. A security guard in paramilitary uniform was standing next to the electronic security gates at the entrance, yawning and looking at his watch.

“Now,” said the chess player, pointing first at the sketch and then at the small chessboard, “have a look at this. We managed to reconstruct the last move made by the black queen, from b2 to c2, but we didn’t know what the previous move by White was that forced her to do that… Remember? When we looked at the threat from the two white rooks, we decided that the rook on b5 could have come from any of the squares on 5; but that couldn’t explain why the black queen fled, since she would already be in check by another white rook, the one on b6. Maybe, we said, the rook had captured another black piece on b5. But which piece? That’s where we got stuck.”

“And which piece was it?” Julia was studying the board. Its geometrical black-and-white design was no longer unfamiliar, but one in which she could move about as if in familiar territory. “You said you could find out which it was by studying the pieces off the board.”

“And that’s what I did. I studied the pieces one by one, and I reached a surprising conclusion.

“Which piece could the rook on b5 have taken?” Munoz looked at the board with his insomniac eyes, as if he genuinely didn’t know the answer. “It wasn’t a black knight, since both are still on the board. It wasn’t the bishop either, because square b5 is white and the black bishop that can move along the white diagonal hasn’t as yet left its original position. It’s still there on c8 with its two escape routes blocked by pawns that have not yet come into play.”

“Perhaps it was a black pawn,” suggested Julia. Munoz shook his head.

“That took me longer to reject as a possibility, because the position of the pawns is the most confusing thing about this game. But it couldn’t have been any of the black pawns because the one on a5 came from c7. As you know, pawns capture by moving one square diagonally forwards, and that one presumably captured two white pieces on b6 and a5. As regards the other four black pawns, they were obviously miles away when they were captured. They would never have been anywhere near b5.”

“Then it must have been the black rook. The white rook must have taken it on b5.”

“No, that’s impossible. Given the arrangement of the pieces around a8, it’s obvious that the black rook was captured there, on its original square, without ever having moved. It was taken by a white knight -although in this case it doesn’t much matter which piece it was captured by.”

Julia looked up from the board, disoriented.

“I don’t get it. That discounts all the black pieces. Which piece did the white rook take on b5 then?”

Munoz gave a half-smile, which was not in the least bit smug; he merely seemed amused by Julia’s question, or perhaps by the answer he was about to give.