When their mother has to go to China on business, headstrong Tom (10) and his siblings Elmar (13) and Nina (15) come to stay with their grandparents in the countryside. But grandma and grandpa still have to remember the grandchildren's visit. The only thing that helps Tom is to see the whole thing as preparation for his Mars mission.
Tom is ten and different from the other children. He doesn't like change, red things and anything loud quickly becomes too much for him. His specialty is space. He loves running around in his astronaut suit and likes to wear a helmet in difficult situations. When his mother unexpectedly has to go to China, Tom and his siblings Nina (15) and Elmar (13) have to move to Grandma and Grandpa's house in the countryside in Lunau for six weeks. This is a disaster for Tom. To make sure he makes it anyway, his mother gives him a logbook and suggests that he sees the trip to his grandparents as a trial Mars mission. Tom's greatest wish is to be the first person to fly there. "If you can do it with Grandma and Grandpa," his mother assures him, "you can do it on Mars too." And so Tom quickly appoints his sister Nina, who is always on the phone, as radio operator and the hyperactive Elmar as first officer. Together with his crew, he tries to explore the planet Lunau and understand Grandma and Grandpa, who seem to live by their own rules.
