At age 38, Eva fears that her biological clock is about to stand still forever, but her fiancée Kat does not want a newborn to upset the free and carefree existence that they both live on a ship in the canals of London. When Roger comes to visit from Barcelona, Eva not only sees in him the best friend of his girlfriend, the best emotional ally imaginable, but also a potential donor. And to Kat's surprise, Roger is attracted to the idea of being a father, despite being a man whose relationships do not usually last more than one night ... so Kat has no choice but to accept the implementation of the plan for fear of losing Eve.