Prominent ear/nose/throat specialists all around the world are dropping dead after opening mysterious envelopes received through the mail. Steed's investigation leads to a nursing academy funded by an eccentric colonel.

A rather weak episode. Tara is definitely not looking like the self-reliant professional that Cathy and Emma were... Or that she herself was in All Done With Mirrors.

Even though the envelopes' contents were powerful enough to kill whoever opened them almost immediately, it seems that anyone who handles them after that is unaffected... Even when Tara picks one up immediately after Herrick's death. In reality, if whatever was in (or on) the envelopes was powerful enough to kill that fast, anyone who handled the envelope afterward would suffer the same fate.

A sneezing sound is heard from two different doctors, right before their deaths, but are not shown to be sneezing on camera. (Obviously the sneezes were dubbed)

  - From my own observations.

Look for the scene wherein Tara is checking the cabinet in her deep frozen prison. She finds two flasks labeled "ether" and "potassium chlorate," this latter showing also a legend that reads: "Allow to dissolve slowly in the mouth." You don't need to be a chemist--although I am--to know how hazardous this substance is. If Tara herself says that potassium chlorate explodes on contact (which under certain circumstances, is true), what person, in their right mind, could take a potassium chlorate capsule into their mouth? All I can say is that potassium chlorate is mainly used in printing, dyeing, matches, chemical analysis, explosives and pyrotechnics (a simple search through the Internet will state this). Now for what reason the scriptwriter thought this chemical could be used in medicine, I just don't know!