Seven months after our divorce, I rushed into St. Jude’s Children’s and Women’s Hospital, still angry at my ex-wife, only to learn that she had just given birth to twin boys, and both of them were mine. Before the night was over, a nurse would place a brass key in my hand and tell me to use it before my own family arrived. And what was waiting for me beyond that was even more shocking.

I unfolded the paper under the harsh fluorescent lights of the garage.

It clearly showed the main estate house, the caretaker’s cottage, the overgrown greenhouse, and a narrow underground service tunnel running under the back garden.

A red line ended at a small square labeled: secondary heating chamber.

“What does this tunnel mean?” I asked, studying the red line.

“It was part of the original coal heating system built a hundred years ago,” Marcus explained.

“Your grandfather had the main entrance sealed off decades ago when the modern furnace was put in.”