A Cruise to Die For — Richard L. Baldwin

Lonely widow, Henrietta Wormly seeks a boarder who will be a handyman and a companion. Against her friends' best efforts to change her mind, she accepts Peter “Lucky” McNeal into her life only to soon see the error of her ways. During a cruise on the Rhine in Germany, the boarder is killed. Lou Searing and Jack Kelly are called in to solve the crime and they do. Justice wins, but only after some good detecting.

Also in A Cruise to Die For, Lou and Jack solve a murder in Muskegon, Michigan involving a boarder. And a summer beach party at the Searing home hosts an entertainer who provides guests with a memorable visit.