Episode Title:Night and Day.Episode Description:On the dark side of the planet Mercury the Houseman and Gray mining crawler breaks down after a rocket capsule explodes. The crew are unable to evacuate and if the crawler fails to get moving again it will be destroyed by the sun's blazing heat. Alan and Brains arrive in Thunderbird 3 to help with the repairs but one problem leads to another and it's a race against time before the sun rises.