This detective/police drama series was based around two mis-matched detectives. Lieutenant James Dempsey was seconded to a new undercover section of Scotland Yard known as SI 10. This was for his own protection following a corruption scandal in the New York police department. Once in London, Dempsey was partnered with a beautiful female Detective Sergeant named Harriet Makepeace, who prefered to be known as "Harry". Together, they worked under the extremely watchful eye of Chief Superintendent Gordon Spikings. Dempsey and Makepeace never really agreed with each other's methods of police work, but they managed to get the bad guys. Michael Brandon and Glynis Barber made the roles of "Dempsey and Makepeace" their own. Their on-screen relationship could never prepare the public for what was to happen in real-life. Michael and Glynis became husband and wife on November 18th, 1989. On November 21st, 1992, three days after their third wedding anniversary, Glynis gave birth to a baby boy, Ale.
New York Police Lieutenant James Dempsey kills his corrupt partner Joey and has to lay low until the case can be further investigated. His superior O'Grady sends Dempsey to London, England as part of an exchange of officers. Chief Superintendent Spikings, head of SI 10, is not to pleased to have a 'yank' forced onto his department. He decides to couple Dempsey with his complete opposite, Sergeant Makepeace, an upper class English rose on a case involving a mysterious shipment of caviar.
Jailbird Charlie Wilson wants to speak to Gordon Spikings alone concerning an urgent matter. But he shuts up tight after his little boy is kidnapped in the park. Meanwhile Spikings finds himself subject to a bombed briefcase while traveling by tube.
Harriet Makepeace's best friend Sarah is raped and murdered on a train to London. The victim's father, Judge Hackett forbids an autopsy done on her body, leading the investigation to focus on one possible suspect seen by Makepeace: a slightly retarded man called John Bates.
When Dempsey is framed by another cop for something he didn't do, Makepeace risks her career to prove his innocence.
Dempsey goes undercover and infiltrates a gang after discovering a link between the London underworld and the New York police department.
Dempsey is stalked by a homicidal women who obsesses over him, and who hates Makepeace for being with him.
Sid Lowe rules an entire London region with an iron fist. When one of Makepeace's informants, Wee Jock gets beat up by Lowe's men, for once it is Dempsey who is the more reasonable one and has to restrain his partner.
Makepeace gets injured while pursuing jewelry thieves with Dempsey. On her first day out of hospital, they run straight into a bank robbery and hijacking - and Dempsey is reluctant to put Makepeace in any kind of danger.
A murderer who is obsessed with Makepeace threatens to kill his hostage within 24 hours if Makepeace will not meet with him.
Dempsey happens to be present at a casino when it is robbed and a security guard murdered. Spikings tells him to wake up Makepeace in the middle of the night and start their investigation.
When the main witness of a trail of a drug dealer threatens to withdraw her statement when her daughter is kidnapped, Dempsey goes to the Bogeyman for help.
After a long night on a fruitless stakeout, an SI 10 colleague is shot by an American hit man right in front of Dempsey and Makepeace. The hunt is on for the killer, who's been targeting a pimp but whose real target seems to be somebody higher up. As luck would have it, one of the prostitutes happens to be an old school chum of Makepeace.
While working undercover, Dempsey comes across a former nemesis from New York City.
When Dempsey is nearly killed during an investigation, Makepeace resigns for good from the police force.
A priceless collection of jade artifacts has been stolen from Makepeace's ancestral home, Winfield Hall. When she and Dempsey join her father's other guest for a weekend pheasant hunt, the search soon turns into an old-fashioned murder mystery.
Makepeace poses as reporter Debby Smith to get close to hoodlum 'Marocco' Jack and ends up saving his life from a rival gang. Dempsey joins Marocco's gang by posing as an American driver called Andy Sallapuccio, whom they need to pull off two simultaneous jewel heists. Meanwhile Spikings is facing complaints from upstairs that might lead to SI 10 being shut down.
Dempsey becomes obsessed with catching a tough guy called Keith Lymon. Makepeace thinks it's because the two men are different sides of the same coin.
Once again, Dempsey and Makepeace are witness to a fellow policeman being shot. In this case it's one of Makepeace's former partners, Tom Bishop, who's dying words involve millions in cash and 'the man in the red coat'.
Dempsey and Makepeace are shadowing Frank Egan, who has just got off Scott free on a murder charge. His next big job seems to involve 'a bird man' and 'haggis'. It leads to Makepeace posing as a floozy and Dempsey as a pilot.
An antique dealer is murdered and priceless Egyptian artefacts are stolen. While the crooks try to find a buyer, Dempsey and Makepeace go undercover and find several parties looking to get their hands on the artefacts.
While investigating a death of a boxers, Dempsey and Makepeace discover a counterfeit money laundering scheme.
Dempsey and Makepeace go undercover as Middle East terrorists to find an arms dealer supplying several terrorist groups in Britain, Can they find the dealer and stop him.
Dempsey and Makepeace witness a young woman being run down on the street. She turns out to have been a model with connections to drug trafficking and members of parliament.
A group calling themselves the African Liberation Army is terrorizing London. During the investigation, Dempsey and Makepeace get into an argument over a misplaced set of car keys which escalates so far that Dempsey decides to turn in his badge and head back to New York.
A truck carrying studio equipment is hijacked. Then it turns out the contents were actually automatic guns meant for a group of Arab terrorists.