Gabriel's mother left - or vanished - a year ago, and while hiking with his friends he finds a crystal that emits shimmering light. Risking an ice-topped river to fetch it, he realises that this is the place where his mother was last seen. He shows the crystal to his science teacher the next day, but it appears ordinary. Through a magnifying glass however, Gabriel sees a white tiger inside....

GABRIEL STONE AND THE DIVINITY OF VALTA is written in a teen-speak manner, with even the third-person narrative saying "Cedric would totally tease them for it." Piper and her pal Brent come in on a science project and Cedric, who dislikes them, follows secretly but the four kids and dog Zigzag fall into the river and through a portal to another world. The countryside looks nowhere like Willow Creek, it's summer and a strange creature is ambling around - quite a large one.

Making for shelter, trying to find Cedric, the three friends encounter a talking monkey (which talks like Yoda), poisonous berries and savage gruocks. Zigzag gets bitten while saving the kids, and next day she starts turning strange and bites Piper. Valta is a land under threat and the friends are warned to get home quickly. But a pit trap lands them in the power of the Empress, guarded by the huge white tiger. She says that the crystal is a divinity stone, and Gabriel has to find a second one for her (like Galadriel, she tells him to be brave, keep the stone secret and she will come to him when he needs her).

I did find some elements derivative, and the monkey talk was just annoying. I was concerned that someone who has fallen into a frozen river isn't urged to get dry, get warm and get home. The swiftness of access to the Empress is a feature of childish fantasies - in tales for older readers, the ruler is generally accessed after layers of waiting rooms, functionaries, appointments and delays. Children unequipped to survive a day's hiking are a strange choice for a quest. But Gabriel's own quest is of course the search for his mother, and he is determined to take any chance of finding her. And then there's Cedric... and shapeshifters... and the gruocks come out each night.... GABRIEL STONE AND THE DIVINITY OF VALTA by Shannon Duffy isn't intended for older teens, but there is plenty of action and likeable characters to keep young readers interested.