Killers of a certain age

Four women--Billie, Mary Alice, Helen, and Natalie--were recruited by an organization called the Museum during World War II to hunt down and assassinate Nazis. After the war, they moved on to other high-caliber criminals. Now they are in their sixties and enjoying a retirement cruise to the Caribbean when they are targeted by one of their own. The women must rely on their skills and each other to survive.