Cyanide is a powerful poison that usually kills it's host instantly and has been used in Espionage stories as a spy's only option to avoid torture or been forced to give information or where the Villain poisons an important figure.
It was first seen in the 1962 James Bond film where a henchman called Jones who is working for SPECTRE operative Dr. No uses it when Bond outmatches him. Bond offers him a cigarette but Unbeknownst to him Jones deliberately trying makes one with a hidden Cyanide capsule and commits suicide by ingesting the substance.
From Russia With Love
Bond's Attachi Briefcase is fitted with this if he has no other option although he takes it and flushes it down a toilet seeing no use for it.
In Thunderball it is revealed that Paula Caplan swallows Cyanide to commit suicide with.
License To Kill
The Police Narcotics agent Kwang is shot and before suffering at the hands of the infamous Drug Lord Franz Sanchez he bites into a Cyanide Capsule and dies.
In Skyfall Bond captures Raoul Silva and takes him to the Mi6 Safehouse to be interrogated. There he Reveals to Bond and M that he was tortured by the Chinese Communists during the Transfer of Sovereignty in 1997 after M sold him to them. After 5 months of Brutal torture and hopelessness Silva still kept a Hydrogen Cyanide (HCN) capsule in his back left Molar. He. Broke the tooth that contained the Capsule then he bit and ingested it. After he did this however the Capsule did not kill him but even worse intenally burned his insides and damaging them as well as dissolving his gums most of his teeth as well as painfully burning away his cheekbone. After he escaped captivity he had to where prosthetic teeth with a false metal Jaw bone and Temporomandibular joint which when is fit into place hides the disfigurement and burns caused by the damage done by the Hydrogen Cyanide.