Lima, Peru — It is early evening when the young man enters the Restaurante San Martin. There are only a half dozen diners seated at rickety wooden tables. He looks around - as much to take in the scene as to locate the man he came to meet.
He moves quickly to the table. Then, a bit in James Bond fashion, he gives the prearranged passwords: ''La luz en el cielo esta extinguiendose'' (the light in the sky is fading).
To this, his newfound companion replies quietly, in English, ''Mr. Fulano, your light shines.''
There is a furtive smile on the young man's bronzed face as he looks around to see if anyone is noticing the encounter. No one is. The diners in the restaurant seemed preoccupied. The young man sits down quickly.
This was the scene as this reporter met a member of the Sendero Luminoso (Shining Path), a Peruvian guerrilla movement that is gaining strength in this Andean nation, at a restaurant located behind the stately arched porticoes facing the Plaza San Martin, Lima's main square.
The Shining Path guerrillas, who came to light 11/2 years ago in the rough environment of the hill country surrounding the old city of Ayacucho 200 miles south of Lima, have now shown themselves in Lima itself.
''We will operate everywhere,'' the young man who calls himself Carlos says. ''There is no part of Peru where we won't be a factor.''
Yet he quickly admits to several recent guerrilla setbacks - including one south of Ayacucho in which at least 30, and perhaps as many as 40, guerrillas were killed fighting an Army patrol.
''That was bad,'' Carlos acknowledges. ''But it was only one battle out of dozens in which we have taken the Army by surprise.
''One battle does not a war lose,'' he says.
We spoke in Spanish, although Carlos said he knew some English - and indeed had understood this reporter's opening greeting to him. Moreover, Carlos was clearly well educated. He sprinkles his conversation with literary allusions.
But he refuses to say where he was schooled and whether he was a student of Abimael Guzman, a professor formerly at the Universidad de San Cristobal de Huamanga in Ayacucho. The professor, a disciple of Mao Tse-tung, is regarded as the ideological father of the Shining Path guerrillas.
Carlos does say he ''came from a middle-class family in Ayacucho'' and that he seldom sees anyone in his family now. ''It is not safe to see them. I am not worried that they would give me away. I am worried that the military knows who I am and would set a trap for me if I were seen near my family's home.''
What motivates him to be a guerrilla instead of seeking change through the country's democratic political structure? He argues: ''This country's society is corrupt. Everything is corrupt. Everything must be torn down so we can build anew.''
Such attitudes are shared by Professor Guzman, who is no longer at the university but who is thought to be somewhere in Ayacucho Province, using the name ''Comrade Gonzalo'' and preaching what Carlos calls ''essential Maoism.''
The Shining Path philosophy blends Christianity with Marxism, and its adherents believe the group ''will eventually sweep this country, ridding it of corruption,'' Carlos said. But Carlos would say little more about the ideology. It appears that philosophical discussions are restricted to closed meetings of Shining Path and not articulated publicly. Some question whether group members actually share a consistent ideology.
What the public sees, however, is evidence of the group's military activity. Some sources in Peru say Shining Path has killed more than 1,000 peasants in the Ayacucho area.
''These peasants stand in the way of our success. Many are government informers. Others oppose us actively, do not cooperate with us, and even refuse us food and sustenance,'' Carlos says.
Carlos responds vehemently to the suggestion that peasants perhaps do not believe the Shining Path cause is justifiable. ''They (the peasants) must, eventually,'' he says.
In a gentler voice, the guerrilla says this reporter ''could not possibly understand Peru's corruption, its immorality.''
Carlos strongly criticizes the United States ''and its own corrupt society.'' He is quick, however, to say the Soviet Union is corrupt, too.
''There is no difference,'' Carlos says, ''between North American and Soviet corruption. Both are bad. But that is for the people of your countries to handle. Our problem is here and we are solving it.'' In the past, Shining Path has also spoken out against Cuba. But this may be changing.
In Lima, where the guerrilla group was not thought to be operating until the past four or five months, recent bomb blasts and shoot-outs between police and ''seditious groups'' are thought to have been the work of Shining Path.
The guerrillas caught the government of President Fernando Belaunde Terry off guard, but it is now forming a counteroffensive.
''Belaunde is a fraud,'' Carlos says. ''But he won't be in office much longer. His term will be up (in 1985). And it will be the next president who we will really have to deal with.''
The hour this reporter and Carlos had together drew to a close and, as he prepared to leave, he reflected: ''I've killed and I can do it again, but I admit it is hard. My Christian training makes it hard, I suppose my understanding of Marxism does, too. But necessity sometimes makes killing right since it is the goal, not the means that is important.''
He then smiled and said: ''Stay away from Ayacucho. It is no longer safe and won't be until we have won.'' Then enigmatically, he added: ''or until we have lost.''