From: Seven By Seven, ed. Tony Burton, Wolfmont Publishing, 2006.
In this 2007 Derringer-winning story from a flash fiction anthology based on the Seven Deadly Sins, Carolyn Hendon receives a phone call from a stranger claiming to have kidnapped her husband. The stranger goes on to describe her husband's car and license plate, but Mrs. Hendon is certain her husband is home. When the stranger warns he isn't bluffing, he will kill her husband, Carolyn tells him to go ahead and hangs up.
A well-executed take on mistaken identities, with an ending I didn't guess.