Several steam engines go missing. As do the elephants at the London Zoo. As well as several famous diamonds, tiaras, and many years supply of tapioca pudding from a pudding factory.
No one makes the connection, but a small boy from a chimny-sweep family goes missing at about the same time.
The trains, elephants, diamonds, tiaras, and spoons smelling of tapioca are found in a large cave in the Scottish Highlands. The trains are mostly broken and the elephants are old and cantankerous by this time. Everything is returned to their rightfull owners. There are no suspects.
Found underneath a pile of beheaded toy dolls and assorted junk in the back of the cave is a pristine and beautiful violin.