There is treasure hidden in the school and the dastardly Councillor Cedric Scrimshanks wants to find it and take it for his own. But Mabel and best friend Jodie are determined to foil the foul plan and save the treasure for the school. It's a close call, but Mabel's special bell ringing technique raises the alarm and uncovers the long-lost treasure.
Mabel can't swim but she is excited to be entering the novelty race in the school's swimming gala. She has built herself a very special boat made out of an old tin bath. But Sidney Scrimshanks is entering the race too and he thinks nothing of cheating to get the gold. It is up to Mabel to make sure that he doesn't succeed in his nasty tricks.
Mabel loves football and plays every break time and after school most afternoons. But one day she hears that the dastardly Councillor Cedric Scrimshanks is selling the school football pitch to a building developer - and just because his son, Sidney Scrimshanks doesn't like football. It is up to Mabel to outwit the mean plan and make sure that the football pitch is there fo all pupils at Old Buttspry Primary School to enjoy.
When the local theatre is looking for extras for a play, Old Buttspry School pupils are the first to volunteer and Mabel gets the part of a bee. But Sidney Scrimshanks is jealous and he comes up with some mean pranks to make sure that Mabel does not enjoy her big performance. It is all down to Mabel to steer clear of the tricks and still enjoy the first night.