Mr Hick�s cottage workroom in Haycock Lane is burnt down one night. Daisy, Larry, Bets and Pip meet Fatty, a new boy in the village and together form the detective club the �Five Find-Outers and Dog� to solve the mystery of the burnt cottage.
Mr Hick returns from London to find his cottage destroyed and his valuable old documents ruined. It was found that the fire was deliberate and petrol was used to start the fire.
The next day the detectives examine the scene of the crime. Pip finds some nettles trampled down in a ditch and broken twigs on a nearby hedge where the arsonist forced their way through. They also find a scrap of flannel on a thorn. Larry finds footprints which show the arsonist wore rubber-soled shoes with criss-cross markings. Fatty makes a drawing of the footprints. Larry and Fatty find out the valet was sacked on the day of the fire. Daisy & Pip find out about another 2 suspects � Mr Smellie and a tramp.
Bets finds the tramp while walking Buster & the five Find-Outers go to investigate. Goon comes along at the same time and the Five hide on a hay rick. Fatty falls off the rick and is badly bruised. The tramp�s shoes are broken and Pip offers the tramp an old pair of his fathers. The tramp�s shoes are not rubber-soled. The children go back to talk to Mrs Minn and find out she was unable to get out of rocking chair on the night of the fire. The detectives obtain Horace Peeks� address as they are given a letter to him to post from Lily.
The children talk to Mrs Peeks, mother of Horace, and find out that he was out of the house the night of the fire. Horace Peeks arrives and refuses to tell them where he was that night.
The Find-Outers get Mr Smellie�s address from the phone book. Larry and Daisy go to visit him. Larry feigns an interest in Mr Smellie�s old papers, which gets him talking. Mr Smellie was out for a walk on the night of the fire. Daisy sneaks off and finds a pair of rubber-soled shoes, one of which she hides up her jumper. Smellie says that the document in the fire were worth thousands of pounds and Mr Hick was insured. The argument on the day of the fire with Hicks was about an old document. The shoe turns out to not match the footprint.
The tramp turns up for his shoes. He admits he saw Horace Peeks hiding by the cottage on the night of the fire and he had someone with him.
The Five go back to see Lily who says she was with Horace on the night of the fire and is in love with him. She admits they hid in the bushes by the cottage, as Horace wanted to sneak in to get the rest of his belongings. Lily says Horace didn�t go near the workroom, but she says Horace saw Smellie on the premises.
Fatty and Larry decide to sneak into Smellie�s house to hunt for more shoes. Fatty gets caught in the street by Goon and he takes the shoe from him. Mr Smellie catches Fatty and Larry in his house. Smellie says on the night of the fire he went to collect some papers he forgot to bring back earlier that day. Fatty claims that Smellie has caused his bruises & Smellie lets them go.
On a picnic the next day Bets finds more footprints by the river, which are the same. Bets follows the footprints which lead back to Mr Hick�s own driveway. This means the person who set fire to the cottage had been at the house again that day. Bets sees Mr Hick and tells him the whole story about how the Find-Outers are trying to solve the mystery. Mr Hick reports the children to Goon who complain to the children�s
parents. The children get into a lot of trouble.
The Five go and apologise to Mr Hick. Mr Hick comments on several Tempest aeroplanes flying overhead. He comment he saw them the other day and there were seven plans. Fatty works out that the Tempests have flown over only twice � today and the evening of the fire. Mr Hick was supposed to be on the London train at that time, which if true would have meant it was impossible that he saw them. This means he was at his house on the night of the fire. The detectives find out that the train always stops outside the village before it arrives at the station. Mr Hick pretended to go to London, slipped back to the house and hid in the ditch. He set fire to the cottage, went back to the railway line and got on the train at its stop before the station. His chauffeur then met him at the station. Buster finds the buried shoes which made the prints.
The Find-Outers are talking about the mystery and are overheard by a fisherman. They feel they can trust him and tell him about the mystery. He tells them to call at the police station the next day. It turns about the fisherman is in fact the Inspector of Police, Inspector Jenks. The tramp is also there and admits to seeing Mr Hick go into the cottage with a can of petrol and set fire to it. He wanted to claim on his insurance policy for the valuable documents. Mr Hick is questioned by the police and admits he set fire to his own cottage. The grey scrap of flannel turns out to be a false clue as it was from Larry�s own coat!