Once the boat was level with the upper part of the canal, the lockkeeper opened the gates. The horse, used to the procedure, pulled the boat silently into the canal beyond.

The constable trudged to the boat and put his foot on the deck. The bargeman and his partner obligingly hauled the corpse out onto the green bank.

As one, we crowded round to see. Middleton lay still, his eyes closed, his body bloated, an ugly gash across his pale throat. Now that I could look at him closely, I saw that he was indeed Denis' man.

The constable heaved a sigh, hands on hips. "Nasty business, eh? Now then, one of you lads run for the surgeon. Though it's obvious he died of having his throat cut, we might as well get it put down right."

Bartholomew whispered to me, "Think Mr. Denis killed him?"

"I would be surprised if he did," I answered. "Somehow, I imagine Denis is… neater. Likely we'd not have found Middleton's body at all."

"Are you going to tell the constable who he was?"

"I have no reason not to."

When I could draw the constable's attention, I took him aside and explained what I knew about Middleton. The constable showed no recognition of the name Denis, thanked me for the information, then said that there was no accounting for the trouble into which foolish Londoners could land themselves.

Bartholomew and I drifted away from the others, looking over the scene.

The lock and pumps stood near the lock house, where the lockkeeper lived. The pond for excess water lay serenely under the clouded sky not far away, a thick stand of trees lining its far bank.

"I wonder that the murderer bothered to drag the man to the lock," I said. "Easier I'd think to drag him to the pond. He'd not be seen in the woods and would not have to pass so close to the lock house and risk awakening the lockkeeper."

"Unless," Bartholomew suggested, "the killer pushed the dead man into the canal, then opened the lock when the chap floated to the gate."