To learn more about the Mysterons (voiced by Donald Gray), Spectrum have devised Operation Sword, the objective of which is to land a spy probe on Mars's moon Phobos in order to capture detailed images of the planet's surface. The first probe is detected and destroyed by the Mysterons but the second, Mini-Sat 5, touches down safely and begins its orbital reconnaissance. Once Phobos has made a full orbit of Mars, the images will be transmitted to Earth, where they will be received at K14 Observatory in the Himalayas.