Three men kidnap Colonel White's daughter, Victoria and threaten to harm her unless the Colonel uses a Spectrum Rhino and help them mount an attack on an armored express train en route to Paris so that they can steal its cargo of $1 billion in gold bullion. But it is all part of a Mysteron plot by Captain Black to incriminate the Colonel in the robbery and thus end his Spectrum career. Whilst Colonel White pretends to go through with the robbery, Captain's Scarlet and Blue must get Victoria back.