The Golden Pince-Nez

Willoughby Smith is an amanuensis, which is a grand word for a secretary, and he dies at his desk at Yoxley Old Place with a golden pince-nez clutched in his hand. His last words are the sort that make policemen groan: "The professor," he says, and then, "It was she." A professor and a woman. The local police can do nothing with that, Inspector Hopkins is called in, and Hopkins, sensibly, calls in Holmes.

The case has the shape of a locked-room problem, and Holmes enjoys locked rooms the way other men enjoy golf. But the pince-nez is the key. It is a woman's pair, gold-rimmed and strong, and glasses like that tell Holmes more about their owner than the owner would ever volunteer. The professor in question turns out to be Professor Coram, a blind old scholar who lives at the house, and the "she" of the dying man's words is a puzzle that Holmes refuses to let the household explain away.

The investigation reaches into surprising places. Mycroft Holmes is drawn in because his own secretary is tangled up in the affair, and the brothers' scenes together are worth the price of admission. Charles Gray's Mycroft and Jeremy Brett's Sherlock agree on very little except the superiority of logic, and watching them work the same case from opposite ends is one of the episode's quiet pleasures.

Gary Hopkins wrote it, Peter Hammond directed. Frank Finlay does double duty as Professor Coram and his servant Sergius, which is the sort of casting that rewards attention. Nigel Planer is Inspector Hopkins, Anna Carteret is Anna, Christopher Guard is the unfortunate Willoughby Smith, with Natalie Morse, Patricia Kerrigan and Kathleen Byron in support. Charles Gray is Mycroft, Rosalie Williams is Mrs Hudson.

The Golden Pince-Nez is a puzzle of the old school, and the series plays it fairly. The clues are all there, including the one in the dying man's last words, and the solution, when Holmes produces it, is the kind you kick yourself for missing.