Ty Crwn is a big house, and it feels even bigger since only a young boy, Hari, and his two sisters, Meg and Enfys, live there. But why are they home alone? Where are Mum and Dad? This little family's big secret is that Mum and Dad no longer live there. In a special film for the whole family this Christmas we'll follow the siblings and their efforts to stay together at the family home as they try to hide the fact they're home alone from the authorities. But the three Teulu Ty Crwn siblings make quite a team. Enfys Medi is a character. In one day she manages to set up her own business on the school yard, give her teacher a lesson on capitalism, and offer romantic advice to her big brother. Enfys Medi is 7 years old. Then, stuck in the middle is Meg. With her dark make-up, her Dr Marten boots and the constant frown on her face she appears to be a teenage rock chick who's too moody to think about anyone else, but does she have a softer side? And then there's Hari. Hari is the bright-eyed older brother who's doing his best to keep tabs on everyone, while also trying to catch the eye of Heulwen, the new girl at school. Despite some bickering, the three are great friends and work as a team to face the world, but what will happen when a strange man starts dressing up as a postman and a window cleaner to spy on them? Teulu Ty Crwn is a musical film about what it's like to be a child facing the world today.