This is the 10th book in Enid Blyton�s mystery series, first published in 1952.
The Five Find-Outers are recovering from the flu. Fatty plays a trick on Bets. He pretends to be asleep and makes animal noises. It turns out he has learnt ventriloquism! Fatty then plays a similar trick on Mr Goon.
Larry finds out that a house �The Cedars� has been broken into and rifled through. The detectives go to investigate. Fatty sees a kitten inside the house and goes in to get it out. In the house, Fatty finds a very small glove, but no other children�s clothes. Mr Goon comes along and catches Fatty coming out of the house. Fatty and Goon are in the house together and Fatty uses his ventriloquism to make animal noises and pretends a man is groaning in the house. Larry finds footprints of Wellington boots outside the house.
Larry lends a book to his neighbour �Erb, who is a bird spotter. Erb stays up at night, looking for owls and his bedroom overlooks The Cedars. He saw a light of a torch in the Cedars at 3:15 am. Fatty dresses up in a disguise and goes out that night. He talks to a night watchman, who tells him he saw a man in his pyjamas and slippers the previous night. The man was heading down a road which leads to the river.