A straight-line international affair opens up for American chemist Whitney Parker when he comes to Copenhagen in answer to Anders Orsted's cabled appeal. News of Orsted's drowning greets him; he is hindered and blocked by his ignorance, and his screening of Orsted's associates and friends is necessarily incomplete and unsatisfactory. Helge, Orsted's sister, is understanding and helpful until Parker is willing to risk Orsted's life rather than his loyalties when they get word that he is alive and to be traded for a secret, hidden German explosive which he has been investigating. A suicide and the abduction of Orsted from behind the Russian border wind up a weekend of excitement and intrigue. Craftsmanship and know-how keep this smooth and diverting.