A dangerous criminal is on the run—and he is also the master of disguise! Could it be Mr Tolling? Or do the Fangio twins know the culprit's real indentity? The Five Find-Outers and Dog aim to find out...with a little help from Eunice.
The thirteenth book in the series introduces Mr Tolling, an old school friend of Fatty's father who comes to spend a week with the Trottevilles so he can attend the coleopterists' conference at a fair in Petersood. Coleopterists are of course beetle-lovers, and not (as the gang joke) owners of collie dogs, growers of cauliflowers, or sufferers from colly-wobbles. Mr Tolling is rather like a beetle himself, a small man with a huge black beard, large glasses and always wearing a dark suit. He's very likeable, even if he is a little boring, always going on about beetles and how fascinating they are. He's extremely eager to get along to the coleopterist meetings, which are being held at Petersood's Town Hall.