Love on the Range (Brothers in Arms #3)
Mary Connealy

Molly gets a job as the housekeeper at Oliver Hawkins's ranch. But really she's with the Pinkertons, spying to find out if Hawkins has abused women and if he's guilty of murder.
Wyatt refuses to let her risk it alone, convincing Hawkins that he's abandoning his own ranch, angered by his two brothers' coming to claim a big chunk of it.
But when another Pinkerton agent gets shot, they realize Hawkins isn't the only danger. The Hunt brothers will have to band together to face all the troubles of life and love that suddenly surround them.