The Enchanted Castle- Edith Nesbit

"Three children – Jerry (bossy), Jimmy (hungry) and Kathleen (sensible) – find themselves standing in front of a bejewelled princess in the garden of an enchanted castle. It is the first day of their summer holidays. Is she really a princess? And if she isn’t, what about her ring which makes the wearer invisible? This ring, combined with the children’s appetite for exploring, sparks a tale full of vivid adventures and extraordinary characters. With ‘ugly-wugglies’ on the loose, statues alive in the moonlight and crimes needing to be solved, there is never a dull moment. Imagination is powerful; magic is possible."