He's a former CIA operative who juggles it all. She's a hard-core investigative reporter. Together, they're invincible.

Buck

Heading called back to the ranch, after my dad dies, I know I have my work cut out for me. As a CIA operative, I can juggle it all. Always have. Always will. But when she needs my help, I can't possibly refuse. After all, she's the sexiest city slicker this Buck has ever seen.

Stella

My heart and soul is in the city. The last place I ever saw myself was on a ranch, getting filthy, and smelling like a barn all day. But I need his help, and he needs mine - whether he realizes it or not. As for him, the most rugged and irresistible man I've ever known, I can make this sacrifice. After all, this city filly could use a Buck of her own.

While each book in the Invincibles series is a stand-alone with its own HEA, they may be more enjoyable listened to in order.