Under Colton's Watch (The Coltons of New York #6)

A killer on the loose
…and an unexpected attraction

There's only one way US Marshal Aidan Colton can protect a pregnant, recently widowed witness from the Black Widow. He takes Ciara Kelly to a safe house to guard her 24/7. But keeping a professional distance from the bristly, independent professor challenges his long-held distrust of serious relationships. In fact, it's harder than he imagined. Especially when the Black Widow has vengeful plans to snare Ciara.