A fire breaks out in the Rocky Mountains, endangering all wildlife there. To make matters worse, one of the Thunderbirds is having a breakdown from family troubles.
In the Alps, a monorail is trapped under an avalanche on the eve of a severe storm, and with air running out for the passengers the Thunderbirds must work fast.
The Thunderbirds must cope with a double crisis: they must disable a malfunctioning missile system, and rescue a spacecraft that is drifting into space.
A alien ship is sighted approaching the sun, creating massive climate changes across the Earth. The Thunderbirds prepare to intercept the UFO, and face the ultimate challenge: the unknown.