Miss Lilly the oak tree fairy

Alice's secret of Miss Lilly and the other oak tree fairies is soon discovered by her pest of a sister and the Thomas boys. When Alice isn't able to save Miss Lilly on her own, who is the unlikely person that Alice ends up trusting to help her escape the Thomas boys? Will Alice and her secret helper be able to protect the fairies from being revealed to anybody else, or will the fairies have to move their homes to another secret place?