The New Cowboy (Harlequin American Romance Series #1530)

Homecoming Cowboy 

Living on her grandfather's ranch, surrounded by her loving brothers and their families, is helping Avery Bannock put her painful past behind her. But ever since Zane Lawson came home, she's been fighting her feelings for the rugged former Navy SEAL who's sworn to keep her safe—in his arms. 

After a decade undercover, Zane's ready to settle in Montana horse country. Buying the ranch next to the Bannock spread was the first step. Now he's got to convince the gun-shy archaeologist that he's the only cowboy for her. As they work together to find out who's stealing tribal artifacts from a nearby reservation, Zane will do everything in his power to win Avery's trust…and turn their budding romance into a mission possible!