The Tomb of the Chatelaine (Heathcliff Lennox, #6)

Murder, mystery and a dog of distinction. Heathcliff Lennox investigates.
A suspicious accident, a dead man's gun and a lost tomb. Strange events disturb the peace of Lanscombe Park, the magnificent country seat of Lord Godolphin Sinclair.
Adventurer, gold prospector and arms dealer, Sinclair has spent a lifetime amassing a fortune with ruthless determination. He's a man frightened of nothing, until he receives a package from the distant past. Someone knows his secrets, they kill, and then they kill again. A game of cat and mouse is afoot, Major Heathcliff Lennox and ex Inspector Swift are called to Lanscombe Park to investigate.