The Grouse Moor Murder

On the lonely Keppoch moor a dense fog was settling while four young sportsmen doggedly continued their "shoot." There was a sudden report and a few minutes later one of the party was discovered seriously wounded. Several days after, when the victim of that unfortunate "accident" was well on the road to recovery in his host's house, he was found shot through the temple.
The local police investigated with unusual thoroughness and ingenuity, and had it not been for one minor fact, the first shooting would have passed as accident, the second as suicide. But that single detail was enough to arouse the suspicions of Francis MacNab whose detective genius is well known to readers of other Ferguson mysteries. The criminal had made none of the mistakes so helpful to the detective, and MacNab was unaided by any of those intuitions which are convenient in fiction but seldom occur in real life.
The result is a study in detection that will meet the approval of the most exacting reader, while a sinister premonition and tense excitement throughout will hold him to the last page. As for attempting to outguess MacNab-Mr. Ferguson's old readers will warn you that it's useless.
(The Grouse Moor Murder was first published in 1934.)