"Yes, I was," the clerk agreed. "That's 'ow come I remember. As 'e were 'er father, she told me, an' 'e were dead, she were doin' what she could ter finish 'is work. 'E worked fer one o' the big companies, Argyll Company."

"She told you that?"

"No. I know that meself. Not that I knew 'im, like, but I seed 'im on the works once or twice. Din't look well. Sort o' pale an' sweatin'. Mind, I seen men like that when they 'as ter go down deep. Scared o' bein' closed in. An' o' the rats an' the water." He shuddered. ''Don't like 'em much me-self."

Monk pressed it a little further, noting down the details, then thanked the clerk and left.

The rest of the day yielded nothing new. Mary Havilland had followed in the footsteps of her father in half a dozen places. Obviously Havilland had believed that the steam engines were dangerous, but had he learned anything that proved it?

Monk turned it over in his mind as he walked back along the dock-side towards the station. It was dark and there was a fine rain. The smell of the tide was harsh, but he was becoming used to it. Even the constant slurping of the water against the embankment and on the steps down to the ferryboats and barges assumed a kind of familiar rhythm. The foghorns were booming again because the rain blinded vision; lights loomed out of the darkness before there was time to change course.

He wondered about Scuff. Where was he on a night like this? Had he eaten? He had shelter, Monk knew that, but had he any warmth? Then he remembered that the chief booty of mudlarks was coal. Very often the lightermen would deliberately knock pieces off their barges into the shallow water for the small boys to get. Perhaps he had a fire. The riverside was full of children scraping by the best they could-like the rest of the city. It was irrational to worry about one.

He forced his mind back to the case.

Had Havilland found anything to make it necessary for someone to kill him? It seemed unlikely. What could it be? Argyll's had had no serious accidents. But Havilland had been an engineer himself, and he knew exactly what their huge machines were capable of, what safeguards were taken, and that Alan Argyll, of all people, would not want injuries or time lost. An unforeseen incident might kill dozens of men, but it would ruin the company.

So what had Havilland imagined?

Had he really learned something so dangerous he had been murdered to hide it? And then Mary had followed in his footsteps and found it also, and in turn been murdered?