A deathbed promise. An impossible task. Will saving a loved one mean losing everything?

New York, 1872. Sadie McGillicuddy's word is her bond. Swearing to her dying mother to always protect her willful sister, she's soon tested when her beautiful younger sibling runs off into the night. Jumping on a San Francisco train in hot pursuit, the resourceful young woman evades a gangland enforcer's unwanted attention with the help of a handsome stranger.

Count Dolphie Westerhoven's future feels uncertain. Grieving a father who just left him penniless, the lone-wolf Austrian is traveling to San Francisco when an intriguing passenger slips into his private carriage. Quick to offer her protection at his aunt's house, he fears there's more to her story when her sister falls into a mob boss's clutches and Sadie is delivered a warning - a severed hand.

With her sister refusing to leave the mob boss's clutches, Sadie despairs of getting them both out with their lives intact. And Dolphie is shocked when his mesmerizing new friend gives him the slip and appears to defect to the gang boss's side, causing him to question if she's been conning him all along.

Can they set things right before they're both caught in an outlaw's trap in this U.S. murder mystery series?