The Multi-Mobile was an advanced vehicle like an armoured tank, capable of performing a wide variety of functions. The Third Doctor and the Brigadier attended a demonstration of its abilities, during which it was stolen by three foreign agents. They intended to use it to attack and destroy the British Nuclear Defence Control Centre. The British Army, the Royal Air Force and UNIT failed to destroy the Multi-Mobile, but the Doctor stopped it by the simple but effective method of putting sugar cubes in its petrol tank, causing the vehicle's engines to seize up while it was crossing the marsh surrounding the centre. The Multi-Mobile then sank into the marsh. (COMIC: The Multi-Mobile)