Good for the circulation.” He set it on the nightstand and left.

Denton took a few sips, and within moments the cup slipped from his hand and shattered on the floor, and he went down, clutching at his chest.

At the hospital the doctors found he’d been poisoned — a deliberate dose, they said, not any accident of an old man’s medicine.

Dax played the stricken son at once, suggesting to the police that his elderly mother must have muddled the pill organizers in her confusion.

But he had underestimated the old man’s grip on life.