A man sitting on a park bench reads a newspaper article headlined "Death at Sea" and knows a murder has been committed.
The man is a travel agent. He had sold someone two tickets for an ocean voyage, one round-trip and one one-way. The last name of the man who bought the tickets is the same as the last name of the woman who "fell" overboard and drowned on the same voyage, which is the subject of the article he's reading.
This may have derived from a story done by Alfred Hitchcock, if the following Hitchcock quotation is accurate: "If you take your wife on a sea voyage, buy her a round-trip ticket no matter what your plans may be."