The navvies told them nothing, and after an hour or so Monk realized he was wasting his time. Instead he took Sutton's advice and sought out a couple of toshers. They were father and son, amazingly alike: both blunt-faced, with a cheerful and sarcastic disposition.

"Sixsmith?" the father said with a twist of his mouth. "Strong feller, not scared o' nobody. Yeh, I knowed 'im. Why?"

Monk allowed Sutton to ask the question. They had already planned what to say. " 'E din't kill 'Avilland arter all," Sutton replied casually. " 'E really thought as the money were ter pay off toshers wot was makin' trouble."

"An' I'm the queen o' the fairies!" the father said witheringly.

"Yer sayin' as yer never took no money?" Sutton asked, his voice almost expressionless.

"Weren't nothin' ter take!"

"Sixsmith's a bleedin' liar!" the son added angrily. "We weren't makin' no trouble, an' wot's more, Mr. Sutton, just 'cos yer catches rats fer the gentry, it don't give yer no right ter say as we were. Yer know that, yer scurvy bastard!"

"I know yer din't used ter," Sutton agreed. " 'Ow about others? Wot about Big Jem, or Lanky, or any o' them?"

"We in't stupid," the father retorted. "Gettin' meself in jail won't 'elp no one."

"Did Mr. Sixsmith know that?" Monk asked, speaking for the first time.

"Course 'e did!" The father looked at him, his face screwed up in disgust like a gargoyle in the lantern light. " 'E's a fly sod, an' all."

"Not fly enough to avoid a cave-in," Monk observed.

"Course 'e were!" the father said intently. " 'E knew as much about streams and wells and clay stretches as any of us. 'E just don't give a toss."

They asked other toshers, but nothing they could elicit contradicted the belief that there was no more trouble than usual, just the odd quarrel or fight. There had been no deliberate sabotage, and the accidents were rather fewer than average for the heavy and dangerous work in progress.

The thing that struck Monk most forcibly, and which he told the others when they went up in the middle of the day, was that in everyone's opinion Sixsmith was an extremely clever and able man who was very well aware of all the risks and advantages of everything he did.

"So he knew about the streams and wells?" Rathbone said grimly. He looked strained. His nostrils flared with the stench he had been unable to avoid. His clothes were spattered with mud and clay, and his boots were sodden. Even the bottoms of his trousers were wet.

"Yes," Monk agreed, knowing what the inevitable conclusion must be. "It seems he did not care about the cave-in."

"Or he may even have wanted it!" Rathbone added. "But why? What is it that we don't know, Monk? What's missing to make sense of this?" He turned to Runcorn and Orme.