Five on Finniston Farm (The Famous Five, #18)(Paperback Edition)
by Enid Blyton by Betty Maxey
There's a ruined castle on Finniston Farm, but only the dungeons remain - and nobody knows where they are! "The Famous Five" are determined to find them - and whatever is hidden in them - but they are not alone. Someone else wants to know, too. The question is: can the Five get there first?