As a belated Valentine's Day treat, we've got four radio mysteries where our detectives are entangled in matrimonial mishaps. As Sherlock Holmes, Basil Rathbone investigates a black widow in "The Book of Tobit" (originally aired on Mutual on March 26, 1945). Philip Marlowe trails a missing wife in "The Persian Slippers" (originally aired on CBS on October 3, 1948), and Sam Spade is accused of eloping in "The Love Letter Caper" (an Armed Forces Radio Service rebroadcast from March 27, 1949). Finally, a wife wants Richard Diamond to protect her husband in "The Simpson Case" (originally aired on ABC on January 18, 1952).