The Path Through the Trees — Peggy Dymond Leavey

Thirteen-year-old Norah Bingham and her mother plan to spend Christmas in the country with Caroline Stoppard, Norah's great-aunt. When her mother is called away on business, Norah goes on her own to stay with the aunt, someone she has never even met. From the start, the woman makes it plain that she does not welcome Norahs company, nor that of Norah's cousins, Andrew and Becca, who arrive two days later. The isolated Stoppard mansion is as dismal as the Ontario winter. But the cousins soon discover there are puzzles to solve. Great-aunt Caroline has many secrets. Among them is the identity of the boy Norah sees in the backyard. Who is he? And why is he watching the house?