“Which brings us back to that word—complicity,” Harper said. “It would require complicity on the part of the adult offspring. No reasonable scenario can be imagined in which the blood is continually taken by force. Even if you locked your victim away, you would be hard pressed to keep him alive for very long. And in Iago’s case, for all his powers, his own nature would work against him. Because any offspring of his would likely inherit at least a measure of his strength of will. Such a captive would almost certainly commit suicide rather than be a toad and live upon the vapor of a dungeon.”

“Iago has obviously managed to produce all the offspring he needed this last quarter-century,” Bernard said.

“Perhaps,” said Harper. “But perhaps only just. Who knows how many times he’s come close to the limit? And all the while leaving no child behind who could grow to adulthood, who could offer him a steady supply of what he needs.”

Bernard gave a slight shake of his head. “Well, why didn’t he think of that before?”

“I believe he has been thinking about it these last twenty-five years.”

“Tell me something, darling,” said Bernard suddenly—and speaking suddenly with peculiar sincerity. “We enjoy our little subtleties, you and I, but—”

“Stop the car!”

They had reached Lonsdale Square.

They had reached Lonsdale Square—and Harper had noticed something peculiar about the house on the corner. This was in spite of the fact that Bernard, at her command, had hit the brakes so hard that the Morris had gone into an hellacious skid. They were corkscrewing insanely through the narrow strip between parked cars. Bernard was wrestling desperately with the steering wheel. Harper was craning her neck to keep the house in sight.

“Interesting,” she said.

There was a gap at the curb beside the garden. The Morris slid into it, bumped up onto the pavement, headed for the garden’s iron gate—then stopped, as Bernard, downshifting, braking, used the concussion to bring the machine under control. It came to rest with two tires up on the curb, two in the street. He gave his companion a glance of mild exasperation.

“Look,” she said to him. “Turn off the headlamps and look.”

Bernard sighed. Killed the lights. Bent his head to peer up through the windscreen at the narrow, gabled building in front of them.

The square was quiet, dark. A claustrophobic crunch of buildings round a tangled winter garden. The narrow façades of the townhouses lanced the sky, irregular, looming, Gothic. The sharp points of their gables seemed to close like teeth on the purple clouds above.