A classic Agatha Christie short story, available individually for the first time as an ebook.A personal advertisement written in code attracts the attention of Tuppence Beresford. When Tuppence suspects that the code involves the Three Arts Ball, she persuades Tommy to attend dressed in costume. Tuppence's suspicions prove to be correct when a murder takes place, but as all of the guests are dressed in masquerade, identifying the killer may be more difficult than first thought...