A soldier with a secret. A daughter with a quest. Can their steam-powered chemistry thrive on the frontier? Kansas, 1870 -- Buck O'Connor rides a horse named regret. Aimless and alone after a brutal loss to the North, he risks heading cross-country to reconcile with an estranged kinsman by helping in a bloody battle to wreck a new railroad. But after he saves a beautiful widow from an overturned carriage, he's shocked to discover she's the wealthy...