SHADOWS are a permanent source of interest to young children. and Margaret Mahy's The Boy with Two Shadows, illustrated by Jenny Williams (Dent, £1.25), has a pinch of mystery and fear (a witch leaves the boy her shadow to mind), and a reassuring ending,
satisfactorily tied up. Another source of interest is treasure hunts and Eric Carle's The Secret Birthday Message (Hamish Hamilton, £1.25) takes you along on one. It is both a book and a puzzle, with holes in the pages for its hero to climb through and a treasure at the end for him to find. I can see four and five-year-olds loving this odd, handsome, handleable book.