In 1978, Bulgarian dissident and playwright Georgi Markov was leaving the BBC London office where he worked and heading home. Waiting at a crowded bus stop, Markov felt a sudden sharp pain in his thigh and turned to see a large man bending down to pick up a black umbrella. The man apologized in a thick foreign accent and hopped into a taxi. Markov found a growing red pimple where he had felt the sting, and came down with a fever that night. Four days later, he was dead, the victim of one of the most diabolical assassinations in modern history — the Umbrella Incident.

Before his death, Markov managed to share with doctors and investigators the enigmatic theory that he had been struck with a poison-tipped umbrella by a Communist agent. While a postmortem examination of Markov’s body revealed no traces of poison, they did find a small, hollow pellet—about as large as the head of a pin—lodged in the back of his right thigh. When news of the incident was disclosed, Vladimir Kostov, a fellow Bulgarian defector and a friend of Markov’s, stepped forward with a similarly strange story. At a train station one day, he had felt a stinging pain in his back. He fell ill for a few days but recovered, and did not report the incident to the police. But when he was examined following Markov's death, an identical pellet was found still embedded in Kostov’s back.

The subsequent investigation of the pellet and the manner of its projection revealed the advanced technology behind the unorthodox murder weapon, leading most to believe the weapon and pellet were KGB-designed. The tiny pellet was an alloy of platinum and iridium, biologically inert metals that would not cause a physical immune reaction. Two holes bisected the pellet, which was so small and hard that investigators concluded they could only have been drilled by high-powered lasers. After a few tests, scientists reported that the pellet had contained a toxin known as ricin, which is widely used, easily produced, and can kill a human in very small doses. The effects of ricin poisoning are not immediately obvious, simulating a gradual but deadly illness.

With the help of the pellet recovered from Kostov, investigators determined that the pellet containing the ricin had actually been coated in a sugary substance, designed to melt at 37 C, the temperature of the human body, slowly releasing the toxin into the bloodstream. Kostov had survived because the coating had failed to melt completely.

Adopting the umbrella as the delivery system, investigators came to believe that the umbrella had functioned as a kind of gun, with an air compression chamber in the shaft ejecting the pellet when triggered from the umbrella handle. The explosion of a normal gun would have burned the fabric of Markov’s jeans and deformed the pellet.

In the ensuing prosecution of the case, one key witness, the deputy interior minister, committed suicide. Another Bulgarian spy believed to have been the operation’s commander was killed in an unexplained car accident. Another was sentenced to prison for destroying key files about the operation. But perhaps scariest of all is the account of Christopher C. Green, a scientist involved in the investigation, who pointed out that most individuals who believe the government is trying to kill them are delusional and paranoid. In a case where the truth was so much stranger than fiction, if Markov had not been of sound mind and a known target, investigators would have normally attributed the death to “febrile illness of unknown cause” and the pellet would likely never have been found.