Agatha Christie 
Man in the Brown Suit 

Newly orphaned archaeologist’s daughter Anne Beddingfeld is off to see the world. After witnessing a gruesome and fatal "accident", following a suspected murderer, and finding a mysterious clue on a scrap of paper, Anne sets sail for South Africa. Sinister happenings ensue, but her newly acquired paternalistic protector, Sir Eustace, will surely see that she comes to no permanent harm. But which of the two masterful men sharing the voyage, Colonel Race and the elusive Man in the Brown Suit, can she trust? Who strangled the dancer Nadina back in England? And what about that film canister of raw diamonds?