Harkup recounts the story how Rasputin's enemies allegedly lured him to a lunch featuring
"cake and [Madeira] wine ... said to be laced with enough cynide to kill 'a monastery' of monks, but it left Rasputin unaffected. He was then shot, at least twice, but was still alive and fighting back against his would-be assassins. At this point he was beaten into submission, tied up in a carpet and dropped into the frozen Neva river. His body was recovered two days later, and a post-mortem revealed that he had died from drowning."
"There are a number of theories that might explain what happened that day:
1. His assassins were terrible poisoners and did not put enough cyanide in the food to kill him, or mistook an innocuous substance for cyanide salts.
2. Rasputin suffered from alcoholic gastritis.
3. Suspecting someone might try and poison him, Rasputin dosed himself regularly with small amounts of poison to build up an immunity to a larger, normally letha. dose.
4. The sugary cakes and wine acted as an antidote to the cyanide.
5. The story is made up and rasputin was killed by a single shot to the head fired by a British secret service agent."
The she analyzes options 1 - 4, concluding that
* As no samples were preserved and the story changed several times (gee, where have I seen that happen lately?), option 1 is impossible to either prove or disprove in hindsight;
* Option 2 is "reasonable and based on good science" in theory, but equally impossible to confirm because there is no conclusive proof that Rasputin did suffer from alcoholic gastritis;
* Option 3 -- the so-called Mithridatism, named for the king of Pontus (135–63 BC), who is alleged to have done this very thing -- would have worked for animal venom, but not for cyanide; and
* Option 4, while needing more research, at least sounds "promising" on the basis of the comparatively limited amount of knowledge available to date
... only to end her analysis with:
"The fifth Rasputin theory is, of course, the most likely explanation."