When Chadwick Newsome, a young American favoured with fortune and independence, becomes entangled in a liaison dangereux with a Parisian temptress, his overbearing mother deploys her future husband, the elderly, amiable Strether, as an ambassador to engineer his safe return. But seduced by the ambient charms of Paris and the bewitching comtesse de Vionnet, Strether soon deserts to Chadwicks side, initiating a sparkling tale of mistaken intentions, comic accident and false allegiances which culminates in the deployment of another, less fallible ambassador - the cold, glittering, ruthless Sarah Pocock.