In 1870s San Francisco, new partners L.D. Cade and Samuel Clayborne are trying to make a go of both their new business and their unlikely friendship.  When they’re  asked by Cade’s lover, beautiful widow  Marjorie Hamrick, to investigate the attempted murder of her friend Athena Givens during a Spiritualist seance, the partners are initially dubious. Givens isn’t popular with the local powers that be, not just because of her Spiritualist work, but because of her fiery Suffragist speeches. But Cade doesn’t have much use for anyone who’d stab a woman in the back, so Cade and Clayborne take up the challenge of not only solving the mystery of the attack, but keeping Givens safe in a city ruled from the shadows by powerful men who want to destroy her by any means necessary. 

Meanwhile, crime boss  Lee Kwan’s charming but conniving brother Fang is preparing to make his move against his brother for control of the powerful Green Dragon Tong. Fang is unhappy with Kwan’s plans to move into more legitimate businesses, especially ones that involve dealing with the “White Devils.”  Kwan’s beautiful and deadly  female assassin, known as  The White Orchid, knows the danger. She also knows she’ll lose her patron’s support if she kills his brother, so  with the reluctant help of her new friend Mei, she tries to enlist Cade to eliminate the threat. Cade swore he’d never repay Kwan’s help by killing for him, but The White Orchid didn’t get where she is without mastering the arts of manipulation in addition to her other skills. In the end, though, it’s Cade’s honor and sense of duty that draws him into a brutal and bloody gang war that threatens his life and the life of everyone he cares for.