“I have a warrant for your arrest.”
“Our arrest!”
“Yes, on a charge of attempting to steal some emeralds, the property of the Marquis of Cockfosters.”
“Impossible,” I exclaimed.
“Yes,” he sneered, “that’s what they all say.”
“But the emeralds are here in this bag.”
“I know they are,” he said. “I’ve just copped you in time. But you’ve been suspected for days.”
“The thing is ridiculous,” I said, striving to keep calm. “We are taking the emeralds back to Lady Cockfosters, and——”
Then I stopped. If we were merely taking the emeralds back to Lady Cockfosters, that is, from one house in Eaton Square to another house in Eaton Square, what were we doing out of the Square?
I glanced at Susan Berry. She was as white as a sheet. The solution of the puzzle occurred to me at once. Susan’s sister was an ingenious fiction. Susan was a jewel thief, working with a gang of jewel thieves, and her request that I would accompany her to this mythical sister was part of a plan for stealing the emeralds.