A novel of mothers lost and found, “Wilderness” is part roaring adventure, part family drama – with a charm that’s all Roddy Doyle’s. While Tom and Johnny are on a husky safari in Finland, their half-sister Grainne stays behind to face the mother who abandoned her. But Tom and Johnny are too caught up in their adventure to think of home – until they find themselves lost in the snow, in a desperate struggle for survival…