It is 2060 and once again Halley's Comet is passing close to Earth. A businessman and his personal assistant decide to mark Halley's comet's latest orbit past Earth by flying their exclusive flying yacht beyond the atmosphere to chase it. Moments later, the pair send out a distress call as they find themselves trapped in the comet's tail, prompting Alan and Scott to take Thunderbird 3 out to tow the thrill-seekers to safety.

During a joint operation between International Rescue and the Global Defence Force, a series of mishaps nearly ends in disaster. In the wake of the botched mission, Colonel Martin Janus takes over the GDF, imposing a strict set of restrictions on International Rescue. As Lady Penelope and Parker attempt to reason with the colonel, they begin to realise that he is not quite what he seems - then it becomes apparent that he really is an imposter working for the Hood.