The mystery of the strange bundle - Enid Blyton

All the Five Find-Outers have had flu this Christmas holiday, so it doesn t seem as if anything exciting could happen. But then a strange robbery, where nothing seems to have been taken, occurs. Mr Fellows, whose house was robbed, seems to have run out in the night and thrown a bundle into the river. A man with a scarred face is seen poking in the river, and the children come across some strangely small children s clothes. It turns out the clothes belong to a ventriloquist s dummy, and the ventriloquist, who Mr Fellows assisted, was working for the secret service. An important message is hidden in the clothes - but the scarred man has stolen them. All but the one most important item - a shoe with a false heel containing the message, that Buster the dog had kept to gnaw.