Returning home form a night at a bouzoukia club shortly before dawn on Feb. 25, Aristotle Kalentzis, 25, was met and arrested by police who had been tipped off by a group of anti-rightist journalists.

Later that day, two of Kalentzis' friends, Evangelos Christakis and Anargyros Kakavas, were taken to security headquarters.

The arrests of the three might eventually lead police to an extensive rightist underground apparatus, bequeathed by the dictatorial government overthrown in 1974, qualified sources believe.

The three have been charged with causing bomb explosions in Athens and with illegal possesion of weapons and explosives.

Kalentzis, 25, is a disciple of Italian neo-fascist "New Order" leader Elio Massagrande and a ranking member of the Fourth of August group, whose street gangs supported the former military government. The Fourth of August is being investigated in connection with a wave of political violence in Athens, most of it directed against political parties, the press and bookshops.

Though it has not reached the level of political violence in Spain and Portugal, it has unsettled nerves here.

After a peaceful transition from dictatorship to democracy, when, in the words of one parliamentarian, "the junta simply evaporated, disappeared," there are growing indications that the right is reorganizing its forces among youth, the politically disaffected, the press and the security apparatus.

Sixteen Greek journalists have been beaten by supporters of the fallen dictatorship, and 36 leftist bookshops have been bombed.All political party offices have been targets of violence.According to a list compiled recently by youth organizations of the political parties, there have been 146 terrorist attacks during the past year.

The three suspects now in Korydallos Prison are the only ones to be arrested.

Athens' Mayor Yiannis Papathedorou, who, along with 37 other mayors was twice denied government permission to organize rallies to protest the spreading attacks, fears that the violence is the first step toward the reactivation of an unofficial rightist security.

"Why now?" asked the socialist mayor. "The purges were never completed. The junta mechanism never disappeared. They moved cautiously during the early stages . . . Now the psychological climate has changed. The torturers from the security police are all walking about freely. The courts have exonerated those involved in the Polytechnic massacre (of November 1973). If there's no just punishment of junta elements, of course, they'll be encouraged to reorganize."

Of the 71 junta leaders, tried and sentenced collectively to 14 life sentences and 591 years in jail, fewer than 30 remain in prison.

This, coupled with the authorities' inability to curb the growing wave of political violence, has jolted public opinion here.

"These people are operating under orders, not on their own initiative," charged Spyros Karatzaferis, a respected leftist journalist who was one of the first to be attacked. "And these orders are known, in some cases, to originate within, the police and security apparatus. I am accusing them officially," he said at last month's emergency session of the Union of Journalists.

After five journalists were beaten by junta supporters at the December funeral of convicted torturer Evanhelos Mallios, in full view of hundreds of uniformed police, Karatzaferis and other Greek journalists set up committees to investigate.

It was they who led to Kalentzis' arrest.

Though Kalentzis has reportedly said little to investigators, his two companions, according to judicial transcripts leaked to the press, have painted a James Bond scenario of contacts with international fascists, circuitous routes to meeting places, safe houses where arms and cash are stashed, and a membership of more than 1,000 activists in the "Fourth of August."

Magistrate Dimitrios Gyftakis, who interviewed 86 witnesses, is reliably reported to have uncovered the existence of five other major rightist groups.

Both the Fourth of August and the international "New Order" function as political parties with the agreement of Greece's Supreme Court. According to Ministry of Public Order statistics, 23 extreme rightist groups exist here.

"Our tolerance gave them the right to react illegally against legality," charged independent member of parliament Hippocrates Savvouras, himself expelled from the ruling New Democracy Party when authorities searched his apartment last winter and uncovered a cache of arms.

Savvouras, a leading figure in the resistance to the dictatorship, said that the arms were "to protect democracy, not to kill it. That is the difference between us and them. We were acting against illegality," he continued. "But Kalentzis, the others, are being covered acandalously by their own people who remain at the Ministry of Justice and within the security police."

Other foes of the government are more optimistic, and are heartened by the present investigation, and by Kalentzis' arrest.

"It's the first time since the fall of the junta," said one young lawyer, "that justice is attempting to find out what's happening. And though the investigating magistrates are not being assisted by the police, they are trying to conduct a thorough investigation . . . Compare them with Christos Sartzetakis. It was the same when he attempted to investigate the assassination of Gregorios Lambrakis," the 1963 probe depicted in the movie "Z."