They sat in silence, Monk still half crouched. The constable at the oars dug them into the water with all the strength he possessed, hurling his weight against them so violently that for several strokes the boat veered and bounced, then he settled down to an even pace and picked up speed.

There was hardly any light now. The late afternoon had drawn in and the overcast sky had robbed what little there was and the rising river mist distorted shapes. Foghorns sounded eerily. The lights of a clipper appeared, shadowed spars towering above them, drifting like giant trees in the sky. They rocked roughly in its wake.

“Where is the bastard?” the sergeant said between his teeth, peering forward through the gloom. “I'll get that swine if it's the last thing I do!”

“Bugsby's marshes,” Monk answered, straightening his legs to sit up properly. “I'll wager he's going downriver again.”

“Why?”

“He'll know we have men in Greenwich, and people who would say where he went. But he knows the marshes and we don't. We'll never get him once he's ashore there in the dark.”

The sergeant swore.

The constable pulled harder on the oars, his back straining, hands rubbed to blisters. The boat sped over the misty, dark-running tide.

The shore loomed up before they were prepared. There were no lights, only the mud banks catching the last of the daylight in thin, shining strips, and the soft, seeping sound of the rising water in the marsh reeds.

Monk scrambled forward and jumped out into mud up to his calves. It took a surprising effort to pull himself loose from its ice-cold, sucking grip.

But twenty yards downstream he could see another figure on a firmer stretch, and the black shape of a boat pulling away, as if it had landed the devil himself and would flee for salvation.

The constable was out behind him, cursing at the mud. Together they squelched and struggled over the slime onto firmer shore, floundering towards Caleb, who was already trying to run.

No one shouted again. They all three plunged wildly through the deepening mist as the rising wind blew wraiths of it around them, then away again.

The sergeant brought up the rear, dogged and determined, swinging inland a little, driving Caleb towards the point, cutting off his retreat back towards Greenwich.

It was another fifteen minutes of exhausting, heartpounding, leg-aching pursuit before at last they cornered Caleb with his back to the river and nowhere else to turn.

He held his gloved hands up, open wide. They could no longer see his face, but Monk could imagine his expression from his voice in the darkness. “All right! Take me!” he yelled. “Take me to your petty little courtroom, and your charade of a trial! What will you convict me of? There's no corpse!