"That is so, lad. Perhaps they entered from this side."
"Will you hold the lantern here, John?" Cyril said.
The sailor held the lantern to the lock.
"There are no scratches nor signs of tools having been used here," Cyril said, examining both the lock and the door-post. "Whether the thief came into the warehouse first, or not, he must have had a key."
The Captain nodded.
"Thieves generally carry a lot of keys with them, Cyril; and if one does not quite fit they can file it until it does."
The shutters of the shop window and its fastenings, and those of the door, were as secure as those of the warehouse, and, completely puzzled, the party went upstairs again.
"There must be some way of getting in and out, although we can't find it," Captain Dave said. "Things can't have gone off by themselves."
"It may be, Captain," John Wilkes said, "that some of the planks may be loose."
"But we tried them all, John."