A bomb goes off every night or so in Corsica, yet another isolated explosion on an island roadside; a police station is riddled with bullets, yet another one-paragraph report in Paris newspapers.

But as Corsica stoically endures its 20-year-old struggle with low-grade terror, rejecting the violence of nationalist militants but resigned to living with outlaws, one man has stepped out of line. By breaking an unwritten code of silence that has stymied prosecution of Corsican terrorism, Jacques Dewez, a nonpolitical businessman of 70, has just put one of the leading militants and his confidant behind bars -- something the will and might of the French government had failed spectacularly to do.

The terrorist threat intensified this fall, as Corsican militants broke a cease-fire and took their bombing campaign to the French mainland; the latest example was a bomb of suspected Corsican origin that went off Monday at the French statistical agency in suburban Paris. French Prime Minister Alain Juppe, whose own offices in Bordeaux were bombed by Corsican terrorists in October, said of Dewez's singular act of courage: "I think we may finally have left ambiguity on Corsica behind."

Dewez also has opened a window on the surreal nature of life on the mountainous little island, known as the birthplace of Napoleon and for little else besides its hardy tradition of murky clan violence. The unlikely hero is a former airline pilot who built a commercial real-estate empire in Paris and who also owns Domaine de Sperone, a resort and golf course designed by Robert Trent Jones near Bonifacio, at the southern tip of Corsica, within view of Sardinia.

A few weeks ago, some well-known associates of Cuncolta, the legal arm of the outlawed Corsican National Liberation Front's Historic Wing, paid a call on the guard's cottage at the golf club, which had been the target of three bombing attempts in 1994. They told the guard to ask his boss, Dewez, to call a certain cellular phone number.

The number was that of Marie-Helene Mattei, a deputy to Cuncolta leader Francois Santoni. Santoni, a k a "the Iguana," was being sought by police at the time after his conviction in absentia on a charge of illegal arms possession. Mattei, a lawyer who has assisted the Corsican separatist cause for 20 years, is also Santoni's girlfriend. The French press sometimes referred to them as "Bonnie and Clyde."

As Dewez told the story to French reporters, and confirmed in a recent interview, Mattei pressed him to meet with an emissary of "you know who" -- Santoni, that is -- at Dewez's Paris office on Dec. 11. The emissary would go by the name "Gulliver."

When the go-between showed up at his conference table, Dewez immediately recognized him as the operator of a restaurant near the golf course and a member of Cuncolta. The group is a rough equivalent of Sinn Fein, the outlawed Irish Republican Army's legal political wing, although the conflict in Ireland is far bloodier. In the 350 bombings reported in Corsica this year, and the 571 last year, casualties have been relatively few. The last recorded death by violence there occurred July 1, when a car bomb killed a nationalist leader and injured 16 others, including several tourists.

Up to a dozen significant militant groups operate on the island, according to news reports and books on the subject. Many have renounced their claims of independence for the island and simply want more autonomy, support for usage of the Corsican language and a better fiscal deal from Paris. "They have no ideology," Dewez said, echoing others who describe them simply as bandits operating under nationalist colors.

Gulliver told him, Dewez said, that his group was desperately short of funds and would require a payment of about $800,000 before Christmas, or "it would be too bad for the future of the golf course." Extortion is a way of life in Corsica, especially in the tourist business, which accounts for an estimated quarter of the island's beleaguered economy.

"They were bloody sure I was going to pay, which was absurd, of course," Dewez said. Asked if he had ever paid money to keep the peace at his resort, Dewez, contradicting some press reports, declared, "Never."

Dewez said he threw Gulliver out of the office, telling him, "If anything happens at Sperone, I will press charges and denounce {Cuncolta} widely in the media." The next day, as promised, the guard house at Sperone was blown up in full view of the guard, who had been escorted outside to watch the reprisal. The front's Historic Wing took responsibility for the blast in an afternoon statement.

Dewez, as promised, told all to police and subsequently to the news media. Authorities promptly arrested Mattei and reportedly confiscated a sawed-off shotgun from her home. They have since brought in Gulliver, whose real name is Andre-Noel Filipeddu.

But the even bigger fish -- acting on "a point of honor the Corsican nationalists still have not abandoned," Le Point magazine noted -- swam into the police station in Bastia, Corsica. In solidarity with his comrade and companion, Santoni turned himself in. They are now in jail in Paris.

According to news reports, Santoni has taken responsibility for the meeting at Dewez's office, but, like Mattei, he claims it was held to discuss one of the 1994 bombings.

The bagging of some of Corsica's leading trouble-making suspects was unusual good news for the French government, which had an embarrassing year in its effort to combat terrorism on the island. Just last week, as the Santoni drama was unfolding, President Jacques Chirac appeared on national television and all but acknowledged that his government had been negotiating with Corsican militants earlier this year even though his top ministers had insisted otherwise. It was Santoni who blew the whistle on the government's denials by publicly identifying the top officials with whom he said he and others had been meeting secretly.

Chirac also acknowledged that police had the chance to arrest 600 terrorism suspects in one sweep last January when, wearing dark hoods, they held a backwoods press conference that was openly tolerated by authorities.

Dewez said in Paris last week that he did not wish to be singled out for his decision, or be held up as a model of courage to others in his business who pay what is sometimes referred to as a "revolutionary tax."

"The law of silence exists, but it's very understandable," Dewez said. "People who live there have to put up with local conditions, and they're not protected by the police, to say the least. One can't be too severe on them."

Dewez spoke of his love for the island and his pleasure at running a business there but said "it has not been particularly attractive as an investment . . . {because} the margin of profit has been consumed by years of this."

Last Thursday, Cuncolta sent Dewez's golf resort a demand that it cease operations or face reprisals. The Domaine de Sperone promptly shut down, probably for the season. "We can't take risks with the golfers," Dewez said. CAPTION: The guard's cottage at Domaine de Sperone was blown to bits to demonstrate the sincerity of a threat.