Her Disguised Cowboy Billionaire. Montana Billionaires, #8

Marti Parker's life is turned upside down when her investigation into a deadly drug cartel puts her and her daughter in the crosshairs of ruthless criminals. Desperate to protect her child, she finds an unexpected ally in Caleb Malone-a billionaire rancher who is not only willing to help her but has his own reasons for wanting to take down the cartel. Caleb is living a double life, hiding his true identity as a DEA agent from everyone, including his young son.
His brother's disappearance while in the same area that Marti's investigation into the cartel is suspicious. When Marti shows up with new leads, Caleb knows he's found the perfect partner to help him bring the criminals to their knees. As they work together, the heat between Marti and Caleb becomes impossible to resist. But with both of them carrying heavy burdens from the past, can they open their hearts to each other while facing the most dangerous threat of their lives? In this fight against time and evil, they'll discover that love might be the one thing worth risking everything for.