 Bob Lawrence (Banks) and his crack-shot wife, Jill (Best) are holidaying in Switzerland when their French friend, Louis Bernard (Frensay) is gunned down, warning them, with his dying breath, of an imminent diplomatic assassination. To ensure the couple s silence, the conspirators kidnap their daughter (Nova Pilbeam). However, Abbot (Lorre) and his comrades have fatally underestimated British pluck.