Unseemly Exposure — Tony Nash

Harry Page, recovered from his gunshot wound, is enjoying a quiet, peaceful life, with not a cloud on his horizon. Hah! He thinks!
There is one person in the world to whom he owes a favor, his friend Trevor Gale, and that favor is asked of him: Trevor's father, the magazine magnate, whose wife was murdered seventeen years ago on the Island of Thassos, is being blackmailed over the existence of a knife. Trevor assumes that his father has murdered someone, but cannot talk to him about it. He asks Harry if he will investigate - the last thing in the world Harry wants to do, but he has no choice.
Beginning in Thassos, with his wife Karen accompanying him, he asks Inspector Antoni Pavlidis if he can see the old murder report, surprised to find that the case is still open.
Pavlidis cannot help him, but gives him the name of the retired inspector who carried out the original investigation and now lives as a hermit in a shack on the mountain.
They not only find his home but his recently murdered body. As Harry is checking it for signs of life he is knocked unconscious. Worse still, when he comes to he finds that Karen has been abducted. He is warned to stop the investigation of she will die.
His options are few, but he is determined to find the answers, no matter what.