Mary Debenham is traveling from Baghdad, Iraq to London. She appears shy, timid, and gentle, but Mrs. Debenham may be keeping more secrets than believed. She tends to get anxious quickly when discussing the murder, and is always questioning something about the delay of the train.  While she has no apparent motive to murder, and does not own a night gown fitting the description, she refuses to explain different pieces evidence. Is Mary just a concerned traveller? Or is she keeping something from everyone else involved?