Her Master Defender (Harlequin Romantic Suspense Series #1869)

A battle-hardened marine and a driven NCIS agent join forces to survive…

Though survival training is Master Sergeant Tristan Michaels's specialty, one of his students has been murdered. And sharing quarters with the ravishing NCIS agent sent to investigate is a challenge his expertise hasn't prepared him for. Tristan has his reasons for distrusting NCIS agents, but Amber Dalton is stirring unwelcome feelings of a different kind…

Despite the fierce attraction between them, Amber is determined not to let it distract her from the mission. But when they're captured by the killers, escape means combining forces and daring to survive freezing mountain terrain.