The five children, Larry and Daisy Daykin, Pip and Bets Hilton, and newcomer Frederick Algernon Trotteville (later nicknamed Fatty from his initials), meet at the scene of the fire and end up solving the mystery together.

They find certain clues including broken-down nettles in a ditch, a footprint in a grassy field and the presence of Hawker Tempest planes (which Mr Hick mentions "flew over" the other day).

The children realise that as Mr Hick claims to have been on the London train when the cottage was burnt, but by his own report saw the planes which flew over the village at the same time, he is contradicting himself.

Fatty finds out that the cottage and the burnt papers Mr Hick describes as 'most important' were insured.

The book also introduces Inspector Jenks, who helps the children and becomes a good friend of theirs.