'A fine craftsman' Ellery Queen

The man in the yellow robe had put the ancient curse of the Nine Times Nine on Wolfe Harrigan. And when Matt Duncan looked up from the croquet lawn that afternoon, he saw the man in the yellow robe in Wolfe Harrigan's study.

When Matt got there, all the doors and windows were locked from the inside. But when the door was broken down, there was no man in a yellow robe in the room, and Wolfe Harrigan lay murdered on the floor. But at the time of the murder the man in the yellow robe was nowhere near the room.

Who better to explain this miracle than Sister Ursula, a nun, whose childhood ambition was to become a policewoman?