Crime, investigation and punishment are all in a day's work to Detective-Chief Superintendent Erskine Powell of New Scotland Yard's Murder Squad. Now, seeking distance from criminal concerns, Powell embarks on a salmon-fishing competition in the Scottish Highlands. But there, in the castle-dotted countryside along the picturesque River Spey, a cold-blooded murderer soon turns Powell's haven into a busman's holiday. A quiet anglers' paradise becomes just as deadly as the mean streets of London.