WHEN DEATH PAYS A CALL he generally leaves a card behind . . . even if it sometimes takes a pathologist to find it. But on the morning that he visited the bathroom at Forstal Farm, he did it incognito. It took a man with a crowbar to break down the bathroom door, and there on the floor was Basil Maplewood, naked, with one foot still hanging over the edge of the bath. Basil was only twenty-one, and in the very pink of health, but the post-mortem didn't help much . . . no violence, no sign of poison. Here is a mystery in a thousand, and one that almost - but not quite - threw dust in the eyes of Inspector Arnold and his colleagues.