Marta is a normal thirteen-year-old girl. She lives in Betulia, a tiny country where nothing exciting ever happens. She's interested in all the usual things for her age (the music group Euphoria, going out with her friends) and she thinks politics is deadly boring until, to get her own back on her arch-rival at school, she stands as a delegate. Hector Rufián Jr is the son of President Rufián, a sinister, corrupt man. But the presidential elections coincide with those for delegates and due to a misunderstanding the inhabitants of Betulia, who are fed up with the same old politicians, vote en masse for Marta, who becomes the country's first female president. Girl power! Marta is in shock. She, a president? But the laws of Betulia are very clear: no president can resign during the first 100 days. Luckily, she has the help of her friends.