The movie was released with the tagline Moscow's toughest detective. Chicago's craziest cop. There's only one thing more dangerous than making them mad: making them partners. It was the first American film allowed to shoot in Moscow's Red Square. The French title of Red Heat is Double Détente, a reference to the Soviet-American détente of the 1970s.
Loudmouthed Chicago PD Detective-Sergeant Art Ridžić (James Belushi) investigates several local murders committed by Viktor's cartel. Suddenly he finds himself partnered with Danko, who has chased Viktor here from Moscow with the intention of capturing the crime baron alive. Danko is frustrated when his lack of a diplomatic license prohibits him from carrying a weapon. He shares his candid observations with Ridžić: "This Chicago is very strange city. Your crime is organized, but your police is not."
Danko and Ridžić pursue Viktor and his henchmen around Chicago. Finally, Danko and Viktor commandeer a couple of Greyhound buses, then engage in a high-speed chase...until Viktor is side-slammed by a train. He takes on Danko in a running, Texas-style shootout (Danko uses a Ruger "Blackhawk" Magnum given to him by Ridžić); Viktor is gunned down. Danko returns to Moscow after exchanging wristwatches with Ridžić as an act of goodwill.