No man is Boon’s equal, no gun more lethal. Boonsri Angchuan travels the trails, riding from town to town with her one and only friend, a portly Arkansan drunkard named Edward Splettstoesser. She has done nothing else for years, her only goal being revenge upon the one man who should have protected her but instead sold her and her mother into bondage. From Texas to the New Mexico Territory, from the filthy backstreets of San Francisco’s notorious Barbary Coast to the ghost town of a depleted placer mine, Boon and Edward navigate corrupt lawmen, hostile Kiowa, a mad judge, and countless gunmen aiming for their heads in Boon’s dogged pursuit of answers—and vengeance.

It’s been a decade since Boonsri Angchuan and Edward Splettstoesser parted ways in California at the bloody end of her original vengeance trail. Now, she finds herself in the middle of a South American war with a new partner to tell the tale, a young Mexican woman named Lily Contreras with a dark past and more than a little blood on her own hands. And Boon’s vengeance hasn’t been doused yet—she is on a mission to find her mother, dead or alive, beginning with the one man she believes can tell her where she is. From the Chilean pampas to the high Pacific seas and the unforgiving Sonoran Desert, Boon and Lily forge a new trail against military madmen, murderous mutineers, cowboy killers, and la Guardia Rural, all of whom will taste the Vengeance of Boon.