“Captain Black intercepts a transporter truck delivering a shipment from the Fairfield Engine Company to a warehouse. After shooting the driver, Jackson, he starts a fire that quickly consumes the warehouse and everything inside. Later, while surveying the wreckage with a fire chief, Mr Fairfield reveals that his company's shipments were newly fitted-out Spectrum Angel fighters awaiting delivery to Cloudbase. At that moment, the ruins of the warehouse are overflown by three aircraft matching those destroyed in the fire.
Meanwhile, the Mysterons have warned Spectrum that they intend to kill one of the Angel pilots. Destiny Angel has left Cloudbase to take a holiday in Paris, and as she is the only member of the squadron currently away Colonel White believes her to be in the most danger. With communications officer Lieutenant Green unable to reach Destiny at her hotel, White has Captains Scarlet and Blue fly to Paris to bring her back to Cloudbase. Scarlet and Blue find Destiny at a café and all three leave for the airport in a Spectrum Patrol Car, only to be ambushed on a country road by the unpiloted Mysteron reconstructions of the destroyed Angel fighters. Cloudbase is alerted and the real Angels, led by Melody, are dispatched to the danger zone.
As the Mysteron fighters target the SPC, forcing Scarlet, Blue and Destiny take cover in a nearby ditch, the Angels arrive to engage the enemy in a dogfight. After shooting down one of the fighters, Harmony takes damage but safely ejects before her aircraft hits the ground. Rhapsody manages to destroy another. The last fighter is eliminated when it deliberately nosedives into the ground with Melody in pursuit. Melody pulls up before crashing. On the ground, the Mysteron attack has reduced the SPC to a smoking wreck, leading Blue to quip that it will be "a long walk to Cloudbase".”
Much of the episode's second half is entirely taken up with an aerial dogfight. The model work here is excellent, and it marks a rare moment in a Gerry Anderson show where little to no music is required to enhance the on-screen action.
Also, the final cut of the episode removed a brief concluding scene in which Destiny finds that a bottle of perfume that she bought in Paris has survived the destruction of the SPC.