The Ghost Tower — Gillian Cross

The night Dot and Ryan take a sneaky Halloween visit to a condemned tower, they discover more than they bargained for when they catch a glimpse of an endangered species of bat. It''s clear that the bat colony and the tower need to be saved, but Dot and Ryan were never meant to be there and it''s not going to be easy to get the grown-ups on side Can they find a way to stop the demolition and save the bats before it''s too late?