It’s an absurd premise: a tennis coach kidnaps someone to train with his player in preparation for the French open, which isn’t going to happen. They practice and train in the middle of nowhere: on sand, in swampland, on a narrow strip of grass. Oh, and they don’t have any tennis balls, or strings in their racquets, or real nets. And they have to keep moving from place to place because there is an unknown threat from an unknown war.