During the Cold War, the KGB has planted covert operatives inside the United States to cripple American infrastructure in the even of a war. The agents underwent intense brainwashing procedures which erased their old identities and give them new ones as ostensible U.S. citizens until they can be activated. Despite the new period of detenté erasing the need for the plot, KGB clerk Nikolai Dalchimsky (Pleasence) goes rogue to activate the agents against his superior's orders. Major Grigori Bortsov (Bronson) is sent to the States to stop Dalchimsky.
This film provides examples of:
- Artistic License Medicine: Barbara kills a hospitalized agent by injecting air from a syringe to create an embolism. However, she uses a tiny syringe when A LOT of air would be needed to cause death.
- Connect the Deaths: After some analysis of the attacks, Borstov finds out that Dalchimsky is activating the Telefon agents in an order that is spelling out his name.
- Contract on the Hitman: Charles Bronson plays a KGB agent sent to stop a Renegade Russian who has stolen a list of Manchurian Agents that could be used to start World War III. In order to ensure that word won't get out about this cock-up, his superiors order a female American Double Agent to kill Bronson once his mission is complete. Fortunately she's smart enough to realise that she'll also get the chop for knowing too much, and the two run off together at the end of the movie.
- Cyanide Pill: Used twice, the first time by a Manchurian Agent (leading to much puzzlement among the CIA as to how a typical American housewife got hold of an obsolete Soviet suicide pill) and the second time by the KGB protagonist to kill a Renegade Russian (first he throttles him, them to make sure he places a pill between the man's teeth and slams his hand against the jaw to crush it).
- Deep Cover Agent: Both the movie and book have this as the primary plot driver. Communists wanted to cause havoc in America immediately prior to an invasion, so they took a few dozen people, hypnotized them extensively so they actually became average American citizens, living perfectly normal lives, until they heard the code phrase which activated them to go destroy some defense facility. The only problem was that they had been forgotten about for a while, so all of the defense facilities were obsolete and/or not being used, which confused the heck out of the American agencies who were wondering why perfectly normal Americans attacked things of absolutely no strategic or military value.
- Disconnected by Death: Bortsov finally corners Dalchimsky in a Texan bar, but can't kill him because there are two policeman there. Dalchimsky ducks into a phone booth, intending to activate the agents via phone. Bortsov has his colleague create a distraction by knocking over a glass case containing a rattlesnake, and amidst all the chaos bursts into the booth just as Dalchimsky is making the connection and throttles him to death with the receiver.
- Fame Through Infamy: While Dalchimsky never provides an explanation about why is he doing what he's doing, one of the In-Universe theories tossed about why he stole the Telefon list and is activating the agents is that he's looking to become famous through the knowledge that he ordered the attacks. The fact that Dalchimsky is activating the agents in an order that will spell out his name if checked lends some credibility to this theory.
- Hitman with a Heart: When ordered by Bortsov to kill an unconscious hospitalized priest, Barbara initially balks. When Bortsov reminds her that she's killed before, she replies that she will only kill when there's a good reason for doing so. Barbara disguises herself as a nurse and does the deed only after Bortsov explains that the priest is an undercover KGB agent; if the agent wakes and starts talking, it may start WWIII, and Bortsov's not willing to take that chance.
- Manchurian Agent: The KGB plant 51 such agents with fake identities in the United States, programmed to commit acts of sabotage on receiving a Trigger Phrase. Unfortunately a fanatical Stalinist opposed to détente steals the list of agents, and the Soviets have to send Charles Bronson to stop him.
- Miles to Go Before I Sleep: The Soviet agents are activated with the Robert Frost poem that is the page quote. They do indeed have miles to go before their mission is done and they are Driven to Suicide.
- Photographic Memory: Major Grigori Bortsov has this ability, which comes in handy for memorising a top-secret list (only two copies exist) of Manchurian Agents. Unfortunately this makes Bronson the third book, and so his superiors give orders that he should be killed as soon as his mission is over.
- Renegade Russian: A KGB clerk, motivated either by Stalinist sympathies or an insane need to write his name in history, steals a list of Manchurian Agent saboteurs in the United States and tries to start World War III. An interesting twist in that the protagonist is a KGB agent trying to stop him. A further twist is that his KGB bosses neglected to inform the new Premier of these agents, so they can't just get him to inform the Americans as they'll be for the chop.
- Sickbed Slaying: A priest who's been brainwashed to commit sabotage is captured alive. Barbara purchases a nurses' uniform from an on-site outfitters shop, while Bortsov (posing as a doctor) rings up the duty nurse and tells her that another nurse will be replacing her, as she's to report somewhere else. The false nurse then injects air into the IV tube of the patient.
- Sleeper Agent: A whole group of them is the titular "Telefon", doubly so because they have been hypnotized into not knowing that they are sleepers.
- Time Marches On: In-Universe, The Telefon sleeper agents' targets that they had been programed to destroy, back on the height of the Cold War, were high-value and if the list had been activated back then (presumably in advance of some kind of all-out attack) it would have crippled America's warfare capability greatly. By the time Dalchimsky starts activating them, though, detente had long since settled in and many of the targets are totally inactive or are on reserve capability—either way, their strategic value is now worthless and the Americans are puzzled why these people would go after such targets and then kill themselves. Borstov's mission is, thus, to silence Dalchimsky before he either manages to luck into activating a sleeper with a target that is still important or that he has made the attacks go for so long that there is no doubt remaining that it's the work of Russian sleepers.
- Treachery Cover Up: Grigori Bortsov is sent to kill Nikolai Dalchimsky so the KGB will not have to reveal the fact it failed to shut down a network of sleeper agents.
- Trigger Phrase:
"The woods are lovely, dark, and deep, but I have promises to keep. And miles to go before I sleep. Remember, (agent name), miles to go before you sleep."
- KGB sleeper agents in the U.S. were brainwashed via drug-induced hypnosis to forget their true identities and live as Americans until they heard a line from Robert Frost's poem "Stopping by Woods on a Snowy Evening", followed by their Russian names. When they heard it, they would destroy a pre-programmed target and then kill themselves. The Trigger Phrase was:
- The technique is demonstrated for Bortsov using the phrase "Cleopatra says there will be snow from the west." This is the scene being spoofed in the first The Naked Gun movie (where the beeping of a watch was the trigger) when Vincent Ludwig's secretary tries to shoot Pahpshmir with an empty gun.
- We Need a Distraction: Bortsov finally corners the Renegade Russian in a rural Texas bar. Because there are witnesses (including two police officers) Bortsov can't just shoot him, so Barbara knocks over a glass container holding a pet rattlesnake. While everyone is screaming and the police are blasting away at the snake, Bortsov bursts into the phone booth the renegade is using and throttles him to death.