Ante Up by Caroline Lee

River “Hart” Hartwell was raised by his Crow grandfather to do the right thing…even when it means sacrificing everything.
For several years, the town of Black Aces, Montana has been under the control of a nasty piece of work, Mr. Augustus King. He’s got the brains and the muscle to keep the townspeople cowed, so no one stands up to him.

Except the Black Ace.
This masked vigilante swoops out of the hills with six-guns blazing, protecting the town from Mr. King’s machinations and economic ruin. He’s a local hero, a folk legend, and everyone–including Regina Vickers, the daughter of the town doctor–would love to know his identity.

With her father under King’s control, Regina is the only doctor available when Hart’s grandfather breaks his leg. At his ranch outside of town, Hart is handed the opportunity to spend more time with the woman he’s always loved. But between King’s suspicions, a ranch to run, the arrival of a mysterious child, and Hart’s midnight masquerades as the Black Ace, there’s not going to be anything “typical” about this courtship at all. If Hart wants to play such a dangerous game, it’s time for him to ante up!