Rich Evans (Kurt Russell), American exchange student’s day at the Leinster School in Ireland is interrupted when a bleeding man drives up to the school and gives Rich a message for his brother Tom (Glenn Corbett), before dying. Rich and his friend Sean O’Connor (Patrick Dawson) are taken from the school by a man who claims to be from the American Embassy, but who turns out to be an Eastern Bloc agent. Rich and Sean make a daring escape and eventually reach Tom, who is an American intelligence agent and not the Irish sales rep for an American steel company as Rich thought. Rich and Sean get off the flight to London Tom placed them on when they spot some of the enemy agents and find Tom in time to save him from other agents, who had grabbed him. They head to Boyne castle, where the message said vital info about an East Bloc defecting scientist was hidden. However Tom is locked up with the real Lord Boyne, while East Bloc agents replace Lord Boyne and his staff. Rich finds the info, but when he calls the US embassy with it, the bad guys are listening in. The imprisoned group help Tom make an ingenious escape from the dungeon they’re locked into. Using a dory and a glider they are able to intercept the East Bloc agents before they can grab the defecting scientist.