Struggling actor Mix Williams has just landed the role of a lifetime. The part? Anyone. Recruited into MI6's covert Understudy Unit, Mix can slip into the minds and bodies of others. His first mission: investigate a breakthrough that could save--or destroy--humanity. But when the scientist behind the Understudy project--and father to one of the team--turns up dead, the unit is pushed beyond its remit and personal limits. As the Understudies scatter across the globe through borrowed lives and fractured clues, whispers arise of an identity-shifting operative far beyond MI6's reach. Will the Understudies uncover the truth before the final curtain falls?.