Five Go To Smuggler's Top - The Famous Five (Book 4)

Uncle Quentin is sending the Five to an acquaintance at Smuggler's Top. Timmy is not allowed to go and George is naturally furious. In the attempts to keep Timmy hidden at Smuggler's Top, the children notice some queer goings-on in the building that suggest that something secretive and wrong is happening right under their noses. They see someone signalling out to sea in the dead of the night. Who is it and what are they signalling for? Will the Five be able to solve the mystery before it's too late?