Max and Maddy Twist's parents were once famous, international detectives – before the evil Professor Sardine ruined their careers, that is. Now they run an ice-cream parlour, and it is the services of their crime-busting Cluedo-champion children that are called upon! Mr Huffendort, a rich Swiss banker is very worried about a series of raids upon banks, carried out by a team of highly-trained St Bernard dogs! Who can be the criminal mastermind behind this evil and cunning plot?