We all need to know where we come from, where we belong. But for David and Nathalie, this need to know is more urgent than for most people, because they are adopted. Brought up by the same parents, but born to different mothers, they have grown up, fiercely loyal to one another, as brother and sister. Their decision, in their late thirties, to embark upon the journey to find their birth mothers, is no straightforward matter. It affects, acutely and often painfully, their partners, the people they work with and, most poignantly, the two women who gave them up for adoption all those years ago, and who have since then made other lives, even borne other children.