Heroes on the Home Front (Soldier Dogs, Bk. 6)

Charlie and Kate know their yellow lab, Buster, would be a perfect soldier dog. So they enlist Buster in the Coast Guard, where he and his handler work to protect US shores from enemy attacks. Then Charlie and Kate discover a coded Nazi message about a submarine landing that will put German spies on US soil. With hours until the U-boat's arrival, can Charlie, Kate, and Buster be the heroes America needs?