Cousins Masha and Rachel Morgenstern board the luxury liner the SS Manhattan bound for New York, desperate to escape the concentration camps that claimed the rest of their family. America offers a safe haven, but to reach it they must survive a hazardous Atlantic crossing.

Among their fellow passengers fleeing the war, each with their own conflicts, secrets and surprises, are the composer Igor Stravinsky, making a new start after a decade of tragedy, and Rose Kennedy, determined to keep her four children from harm. Particularly worrying to Rose is her daughter Rosemary, a vivacious but troubled woman whose love for a Californian musician may derail her family’s political ambitions. And then there’s young Thomas, a Nazi with a secret …

But, under the waves, the Manhattan is being stalked by a German U-boat. Will any of those aboard the ocean liner ever achieve their dream of a new life in America?