If you're lucky, the mysterious something missing from life is found right in front of you despite the risk.

Widowed Lillian Fernsby has been buffeted by life's ills, and the grief is sometimes unrelenting. Keeping sadness at bay by making merry or being an outrageous flirt is all well and good, but what she really wants is to marry again. When her brother's best friend comes back into her life to protect her from an unidentified stalker, she's intrigued by the mystery and challenge he represents.

The Honorable Thaddeus Carrington is the third son of a viscount, but he refuses to hang upon his father's coattails or put much stock in family pressure to marry. As a Bow Street Runner, he adores the thrill of solving cases, but when he's tapped to guard the sister of his best friend from a disturbing threat, he struggles between remembering her as a young schoolgirl, as well as his confusing new awareness for her as a woman.

While a flirtatious game of cat and mouse begins between them and desire builds, Lillian's pursuer grows bolder, and Thaddeus pledges greater vigilance in keeping her safe. Peril reaches a breaking point one spring evening, throwing the important things of life into sharp relief and threatening their romance. Only they can decide if they want to fight for love before disaster—and death—strikes.