Hollywood sensation, Betty Massino, has come to star in the theatre down the road and Piotr and his friends Andrew and Minnie couldn't be more excited! But when the famous actress's hugely expensive diamond necklace goes missing, Piotr's dad, a security guard at the theatre, is a prime suspect. With the help of Sylvie and her twin sister Flora, can Piotr, Andrew and Minnie solve the crime?