“Go and look at the Thames if you don’t believe you’re here,” Frank grunted. “Then you’ll blinking know we’re in London. And take that dog for a walk while you’re at it, see if you can get her to drop before setting off on your blinking suicide mission.”

He stomped away, hands deep in the pockets of his patched jacket. Lotti and Ben watched him go, thunderstruck.

“Jim,” whispered Lotti. “What does he mean, get her to drop?”

Jim scratched his head. “Lawks, this is awkward,” he said. “Frank just worked it out, while we was coming down the locks. Elsie’s pregnant, that’s what. She’s going to have puppies. And she’s pretty far gone, I’d say.”

“Puppies!” breathed Lotti, after Jim had gone.

“Puppies …” echoed Ben.

They looked at each other in awe.

“Do you think …” Ben tilted his head toward Federico.

“Of course,” said Lotti. “Who else would it be?”

“It’s a lot to take in,” said Ben carefully. “I think I need to go for a walk.”

“Yes,” agreed Lotti. “Me too.”

Side by side, with Elsie lumbering behind them and Federico trotting ahead, they headed away from the Sparrowhawk in the direction of the Thames, wrapped in thought.

Puppies! Lotti walked in a starry-eyed daze. Tiny little baby puppies! Soon—very soon, if Jim was right—they would be not just Ben and Lotti and Elsie and Federico living on the Sparrowhawk but a whole family …

How many of them? wondered Ben, chewing his lip. Would they be girls or boys? How did one look after newborn puppies? What did they need? And what if they came when they were out on the Channel? Would it be dangerous? What if something went wrong, and Ben was at the tiller, and couldn’t help?

They had walked around the basin to the row of buildings on its southern edge and turned into a narrow alley between a chandlery and a pub. Something in the air changed as the light ahead grew brighter. The wind picked up, bringing with it a smell of river mud, laced very faintly with salt. At the end of the alley there was a wall, with steps leading up to the top. Lotti and Ben climbed them together, and gasped.

They had found the Thames.

As it flows east through London, the Thames at high tide swells as wide as four hundred and fifty feet at Woolwich. At Brentford it is still relatively modest, at about a hundred yards across. And though a hundred yards may seem a lot when you have been used to canals, it was not the size of the river that struck Ben and Lotti, but its strength.

Massive, gray, turbulent and sullen, the Thames pushed its way westward on the incoming tide, possessed of infinite energy.