Murder in Store — Pamela Hill

Eighteen year old Sally evades her schoolteacher aunt in Scotland and takes a job in the cosmetics department of an old-established London store. Dry rot in its attics leads to the discovery of old bloodstains connected with a murder hushed up more than a hundred years earlier, and the store, now owned by Millionaire Oscar J. Schussler, is the scene of both modern drug-running and ancient murder.