Thunderbird 2 hovers above the water. With a crash, its huge pod falls towards the ocean surface. A door opens. A ramp extends. Then, with a roar, Thunderbird 4 glides into action; ready to tackle any water-based emergency thrown in International Rescue's direction. Join Thunderbirds Unseen as we uncover the behind the scenes secrets of this beloved launch sequence. In this extra instalment of our behind the scenes investigation of the creation of Gerry and Sylvia Anderson's classic television series Thunderbirds, we take an in-depth look at the Thunderbird 4 launch sequence. With the help of newly unearthed 35mm film and studio documentation, this series challenges some of the "established" facts of the series' early days and uncover footage unseen for sixty years.