This collection features short stories which chronicle the spirited yet friendly rivalry between detective Jack Barnes and Robert Leroy Mitchel, ‘the gentleman who imagines himself to be able to outdo detectives in their own line of work,’ which originated in the mystery novel An Artist in Crime, published six years earlier in 1892. Many of the stories centre around jewel heists, as well as tales of kidnapping, forgery, and The Promissory Note, a locked room mystery with a surprising twist.