The Case of William Smith — Patricia Wentworth

For seven years William had worked as a woodcarver for the local toyshop, ignorant of his true identity. The war had robbed him of his memory, and no one expected him to find the answer. When William is mysteriously attacked in the street, Miss Silver is called in to help.
Is the attack linked to his forgotten past? Or his recent visit to Eversleys Ltd? As the attacks on William escalate, he and Miss Silver must look into his past to stop them from striking again.