After Alicia Velorus' father is convicted as a communist spy, CIA asks her to prove her loyalty by getting close to her father's friend, who's a suspected arms dealer. In the meantime she and her CIA contact Devlin fall in love.

During routine maintenance of a liquid-fuelled ICBM, the fuel tank is penetrated by a falling spanner. The film traces the efforts of the maintenance crew and associated military and civilian personnel to recover the potentially disastrous situation before the fuel tank is sufficiently depressurised that the stack collapses and explodes.