Shadow in the Darkness (Holt Agency Crossover Novel) - Shadow SEALs

It was supposed to be a vacation, not a mission. When Grant takes off on a cruise through the Panama Canal with several of his SEAL buddies, the last thing he expects is drama. And he certainly isn't prepared to find himself in a warzone. Callie is on a much-needed vacation with her girlfriends. Laughter, partying, drinking-maybe a bit too much drinking that first night. The sexy man who helps her back to her room might be a fun cruise hookup. When all hell breaks loose, the fun times come to a screeching halt.
Apparently, the relaxed, easy-going man she's been flirting with isn't quite as average as she believed. But then again, neither is she.