One lucky morning ... Mrs Gaskitt opens the post and finds she's won a prize! Next she kisses the postman! Never mind, though - the postman is Mr Gaskitt doing his very latest job. Meanwhile, Gus and Gloria get a new teacher, Mrs Plum, with silvery hair, a big smile and a huge suitcase, who is ever so helpful when things start to go missing in the classroom. And then Mrs Gaskitt finds she's won another prize! What happens next?