It is a plot as much of skulduggery as any John Le Carre novel. But it is all true.
The story began three months ago when a very highly placed Romanian secret service agent, who goes only by the name ''Mr. Z,'' contacted his French counterparts. He said he wanted to defect and claimed he had been sent to France to assassinate two prominent Romanian dissident writers, Virgil Tanase and Paul Goma.
Mr. Z offered unlimited cooperation in unmasking the secret ploys in the West of Romanian leader Nicolae Ceausescu. But he insisted that he was being watched by his own colleagues and that the Tanase-Goma assignments must somehow be faked.
So French spies arranged to have Mr. Z and another of his colleagues invited to a cocktail party along with Mr. Goma. Using a sophisticated pen, Mr. Z squirted a colorless yet deadly poison into Goma's drink.
Then a French operative jostled Goma's arm, spilling the lethal liquid. Bad luck, Mr. Z told his colleagues.
For Mr. Tanase, an even more elaborate setup was conceived. French authorities simply kidnapped him off a Paris street in front of numerous witnesses May 20. Police were alerted and Mr. Tanase's friends rallied public and press support for an investigation into what appeared to be an abduction by Romanian secret police.
But Tanase was ensconced in a small house in Britanny. His wife and children soon joined him - though only after she filed a missing persons report so an unknowing magistrate could open an official inquiry.
French authorities played outrage. President Francois Mitterrand even canceled a trip to see Mr. Ceausescu because of the kidnapping.
Meanwhile, Mr. Z returned to Bucharest, where he was officially congratulated by Ceausescu and given a medal for dispatching Tanase. It was easy for Mr. Z then to obtain passports for his wife and child for a vacation in France. In mid-August, they arrived in France and were given political asylum. Mr. Z followed a week or so later.
With Mr. Z safe, the French daily Le Matin was able to publish the details of the caper Aug. 31. The same day Tanase, Goma, and Mr. Z appeared at a press conference and verified the facts.
Tanase looked tanned and relaxed. The black-bearded Mr. Z, nervous in his impeccable gray suit, seemed like a young rising business executive.
In fact, he said, he had been in France for eight years, specializing in industrial espionage for Romania while working as an engineer at a French company. He gave a searing indictment of what he described as the dictatorial regime of Ceausescu.
''In February, I received orders to kill Tanase and Goma,'' he began. ''I knew,'' he said, ''that it was a personal order from Ceausescu, who was upset because of Goma's dissident activities and an article written by Tanase.''
''I could not bring myself to carry out this mission and I told DST (the French counterintelligence service) about it in early April. At my suggestion they put the scenario into effect.''