Halley's Comet is passing close to Earth. Businessman Francois Lemaire, on an ego trip sending live pictures back to earth, with his unimpressed wife Melanie on board his space yacht the Solar Wind. They fly into the comet's tail and the ship is damaged losing communications. John in Thunderbird 5 monitoring the situation despatches Thunderbird 3 with Alan and Scott to look for survivors. Alan is particularly excited to be going to Halley's comet.