“I won’t, Princess. I’ll suppress my homicidal impulses, but only out of devotion for you.”

“I’d be eternally grateful.”

“I should hope so.” He looked at his wristwatch as if he didn’t trust the clock on the wall, an old present of his. “But the swine isn’t exactly punctual, is he?”

“Cesar.”

“All right, my dear. I won’t say another word.”

“No, go on talking.” Julia indicated the painting. “You were saying it was something to do with a chess problem.”

Cesar nodded. He made a theatrical pause to moisten his lips with a sip of gin, then dry them on an immaculate white handkerchief he drew from his pocket.

“Let me explain” – he looked at Menchu and gave a slight sigh – “to both of you. There’s a detail in the inscription we haven’t noticed until now, or at least I hadn’t. Quis necavit equitem can indeed be translated as ‘Who killed the knight?” And that, according to the facts at our disposal, can be interpreted as a riddle about the death or murder of Roger de Arras. However, that phrase could be translated in another way.“ He looked thoughtfully at the painting, assessing the soundness of his argument. ”Reformulated in chess terms, perhaps the question is not ’Who killed the knight‘ but ’Who captured, or took, the knight?“ ”

No one spoke. At last Menchu broke the silence, her face betraying her disappointment.

“So much for all our high hopes. We’ve based this whole story on a piece of nonsense.”

Julia, who was looking hard at Cesar, was shaking her head.

“Not at all; the mystery’s still there. Isn’t that right, Cesar? Roger de Arras was murdered before the picture was painted.” She got up and pointed to the corner of the painting. “See? The date the painting was finished is here: Petrus Van Huys fecit me, anno MCDLXXI. Two years after Roger de Arras was murdered, Van Huys chose to employ an ingenious play on words in order to paint a picture in which both victim and executioner appear.” She paused, because another idea had just occurred to her. “And, possibly, the motive for the crime: Beatrice of Burgundy.”

Menchu was puzzled, but excited. She’d shifted to the edge of the sofa and was looking at the Flemish painting as if she were seeing it for the first time.

“Go on. I’m on tenterhooks.”

“According to what we know, there are several reasons why Roger de Arras could have been killed, and one of them would have been the supposed romance between him and the Duchess Beatrice, the woman dressed in black, sitting by the window reading.”

“Are you trying to say that the Duke killed him out of jealousy?”

Julia made an evasive gesture.

“I’m not trying to say anything. I’m simply suggesting a possibility.” She indicated the pile of books, documents and photocopies on the table. “Perhaps the painter wanted to call attention to the crime. Maybe that’s what made him decide to paint the picture, or perhaps he was commissioned to do it.” She shrugged. “We’ll never know for certain, but one thing is clear: the picture contains the key to Roger de Arras’s murder. The inscription proves it.”

“The hidden inscription,” Cesar corrected her.

“That gives further support to my argument.”

“What if the painter was simply afraid he’d been too explicit?” Menchu asked. “Even in the fifteenth century you couldn’t go around accusing people just like that.”

Julia looked at the picture.

“It might be that Van Huys was frightened he’d depicted the situation too clearly.”

“Or else someone painted it over at a later date,” Menchu suggested.

“No. I thought of that too and, as well as looking at it under ultraviolet light, I prepared a cross section of a tiny sample to study under the microscope.” She picked up a piece of paper. “There you are, layer by layer: oak base, a very thin preparation made from calcium carbonate and animal glue, white lead and oil as imprimatura, and three layers containing white lead, vermilion and ivory black, white lead and copper resinate, varnish, and so on. All identical to the rest: the same mixtures, the same pigments. It was Van Huys himself who painted over the inscription, shortly after having written it. There’s no doubt about that.”

“So?”

“Bearing in mind that we’re walking a tightrope of five centuries, I agree with Cesar. It’s very likely that the key does lie in the chess game. As for ‘necavit’ meaning ‘took’ as well as ‘killed’, that never occurred to me.” She looked at Cesar. “What do you think?”

Cesar sat down at the other end of the sofa, and, after taking a small sip of gin, crossed his legs.

“I think the same as you, love. I think that by directing our attention from the human knight to the chess knight, the painter is giving us the first clue.” He delicately drank the contents of his glass and placed it, tinkling with ice, on the small table at his side. “By asking who took the knight, he forces us to study the game. That devious old man, Van Huys, who I’m beginning to think had a distinctly odd sense of humour, is inviting us to play chess.”

Julia’s eyes lit up.

“Let’s play, then,” she exclaimed, turning to the painting. Those words elicited another sigh from Cesar.

“I’d love to, but I’m afraid that’s beyond my capabilities.”

“Come on, Cesar, you must know how to play chess.”

“A frivolous supposition on your part, my dear. Have you ever actually seen me play?”

“Never. But everyone has a vague idea how to play.”

“In this case, you need something more than a vague idea about how to move the pieces. Have you had a good look at the board? The positions are very complicated.” He sat back melodramatically, as if exhausted. “Even I have certain rather irritating limitations, love. No one’s perfect.”

At that moment someone rang her bell.

“It must be Alvaro,” said Julia, and ran to the door.

It wasn’t Alvaro. She came back with an envelope delivered by a messenger. It contained several photocopies and a typed chronology.

“Look. It seems he’s decided not to come, but he’s sent us this.”

“As rude as ever,” mumbled Cesar, scornfully. “He could have phoned to make his excuses, the rat.” He shrugged. “Mind you, deep down, I’m glad. What’s the rotter sent us?”

“Don’t be nasty about him,” Julia said. “It took a lot of work to put this information together.”

And she started reading out loud.

Pieter Van Huys and the Characters Portrayed in “The Game of Chess”:

A BIOGRAPHICAL CHRONOLOGY

1415: Pieter Van Huys born in Bruges, Flanders, present-day Belgium.

1431: Roger de Arras born in the castle of Bellesang, in Ostenburg. His father, Fulk de Arras, is a vassal of the King of France and is related to the reigning dynasty of the Valois. His mother, whose name is not known, belonged to the ducal family of Ostenburg, the Altenhoffens.

1435: Burgundy and Ostenburg break their vassalage to France. Ferdinand Altenhoffen is born, future Duke of Ostenburg.

1437: Roger de Arras brought up at the Ostenburg court as companion in play and studies to the future Duke Ferdinand. When he turns seventeen, he accompanies his father, Fulk de Arras, to the war that Charles VII of France is waging against England.

1441: Beatrice, niece of Philip the Good, Duke of Burgundy, is born.

1442: Around this time Pieter Van Huys painted his first works after having been apprenticed to the Van Eyck brothers in Bruges and Robert Campin in Tournai. No work by him from this period remains extant until…

1448: Van Huys paints Portrait of the Goldsmith Guillermo Walhuus.

1449: Roger de Arras distinguishes himself in battle against the English during the conquest of Normandy and Guyenne.

1450: Roger de Arras fights in the battle of Formigny.

1452: Van Huys paints The Family of Lucas Bremer. (His finest surviving work.)