It's Sioned Siop's birthday today. But after Dion Diogelwch forgot to organise a party last year, Sioned Siop tells him she's too busy to celebrate this year. Is it too late for Dion Diogelwch and the Parc Glan Gwil crew to pull together the perfect surprise party for Sioned Siop? Who will sort the food and decorations? What about the presents?