Locked Room Mysteries In Real Life - Sherlock S03E02 The Sign of Three

There's been a bit of criticism levelled at the central mystery of Sherlock - The Sign of Three. The crime has been called both unrealistic and impractical.

In an unlikely case of truth proving stranger than fiction, the events in Sherlock - The Sign of Three are actually based on a real-life crime.

Sherlock's best man speech. What could go wrong?

(Spoilers below)

Sherlock S03E02 - The Sign of Three

Alfie Enoch as Private Bainbridge

The primary case(s) at the heart of The Sign of Three is the death of Private Bainbridge of Her Majesty's Household Guard. Killed in a locked shower with no sign of the murderer, Sherlock begins to suspect the murderer could strike again at John's wedding. Sherlock identifies the potential second victim as Major James Sholto, and manages to determine the method of the crime before Sholto is killed.

The concept of the case is a classic locked room mystery (Sherlock even refers to it as such upon finding Bainbridge's body). The method - the victim was stabbed by a very sharp blade that penetrated his uniform imperceptibly - fits neatly within the "fatal wound was inflicted prior to the victim entering the locked room" category. The Sign of Three offers a slight twist on this format by making the victim(s) unaware of their wounds (their tight fitting uniforms act as a tourniquet and prevent blood-loss while worn).

Fans of the show were quick to point out that (a) there's no way someone could be fatally stabbed and not know it, and (b) the uniforms would not prevent the wound from bleeding out. Fascinatingly, they seem to be wrong on both counts.

In 1898 Empress Elisabeth of Austria was assassinated using a very similar method. Italian anarchist Luigi Lucheni, feigning a stumble, bumped into the Empress and stabbed her with a sharpened needle file as she was about to board a steamship. The Empress collapsed, but was helped up to her feet and continued to walk the short distance to the boat and up the boarding ramp. Whilst onboard she lost consciousness, but revived after her lady in waiting cut the laces of her tightly fitting corset. The Empress said that she felt no pain, and enquired as to what had happened before collapsing once again.

An artist's impression of the assassination. Source: Wikipedia

While the crime depicted in Sherlock - The Sign of Three does take these principles further than the actual events, the concept itself is founded in reality. Empress Elisabeth's autopsy revealed that the blade had penetrated the heart, but because of the sharpness and thinness of the file the wound was very small. Elisabeth's corset had prevented haemorrhaging, and she had therefore been able to continue relatively unhindered after the initial attack.

More examples of locked room or impossible crime fiction imitating reality can be found here.