They were reported missing on April 8, 1985. The U.S. Embassy undertook an investigation, which was inconclusive. Guatemalan officials said they knew nothing.

To Blake's affluent family in Chestnut Hill, the official response appeared to be a hasty dismissal. Nobody seemed to care what happened to Blake, 27, and his friend Griffith Davis, 38, of Scranton.

So the Blakes began their own investigation. They hired a private detective and enlisted the help of other free-lance journalists who knew Blake. Blake's younger brothers, Randy and Sam, thought their own embassy was lying to them. They traveled to Central America to explore Guatemala's murky underworld, trying to verify scraps of information independently.

They discovered that the truth can be a rare commodity in Guatemala. They were buffeted by rumors and changing stories, and their theories about Blake's disappearance have swung across the spectrum. And the politically conservative parents and their liberal sons became more and more divided over how the investigation should be conducted.

Today, they have little more understanding than they did a year ago of what became of Blake and Davis in the beautiful, mist-shrouded hills of Guatemala.

"Even at this late date," said his mother, Mary C. Blake, "we don't know for sure what happened."

*

From the outset, Nick's brothers suspected that the military had killed a couple of enterprising journalists. Guatemala's archbishop and various human rights agencies had blamed the military for most of the tens of thousands of disappearances in the country since the army took control of the government in 1954.

A few weeks after the disappearances, Gen. Oscar Humberto Mejia Victores, then Guatemala's military ruler, told a news conference that the two missing gringos probably were "with the guerrillas, writing an article in their favor, or they are being used by them to tarnish Guatemala's prestige."

Mejia denied that the military was involved, but then, Mejia had always denied that the military was responsible for disappearances.

Unsatisfied, Blake's brothers began their own inquiries. "They may get away with it with these peasants," Sam said, "but they're not going to get away with it with me."

Stoked up on outrage and equipped with gold American Express cards and connections in high places, the brothers set off to Guatemala.

They knew that Blake and Davis had reported their movements to a military garrison before their trail disappeared. They knew also that the family's investigator had talked to a witness who reportedly saw two tall men, one a blond like Nick, being hustled into a military helicopter at about the same time.

And they knew that Nick's landlord said he had received a typewritten note after the disappearence, saying that Nick was with the guerrillas and that the landlord should "tell friends, not authorities." But they were told that such notes are a common ruse used by death squads to mislead investigators.

Nick Blake had told friends that he wanted to interview a physician who had left her wealthy family in Guatemala City to join the anti-government Guerrilla Army of the Poor, known by its Spanish initials, EGP. It was the type of story Nick liked, Sam said. "He was most interested in humanitarian stories, not high politics."

*

Nick had been a reporter on a small New Hampshire newspaper after he graduated from the University of Vermont in 1979. "But that sort of reporting didn't suit him," his mother said. "He wanted to write more active stories." About four years ago, he went to Central America, where the action was.

There, he joined the ranks of journalists working as single proprietors, mostly young reporters who scratch a living selling their work to newspapers. The fortunate ones have steady outlets with a few big dailies. Blake, like most of the free-lancers, would work for a few weeks on a story and sell it for perhaps $100 to papers. There were no expenses paid and no guarantees.

Nick's family approved of his life, although they were worried. "Ever since I saw the movie Missing, I was afraid something like that would happen," said Mary Blake. The film depicts a family's search for an American free-lancer, not unlike Nick, who was kidnapped by the army in Chile.

According to his associates in Central America, Blake understood the risks and knew how to minimize them. Two months before his hike in Guatemala, he ventured with another journalist for three weeks into guerrilla-held territory in El Salvador, making certain to report his movements to the military until he entered the rebels' turf, where he switched to reporting his movements to the local guerrilla comandante.

While El Salvador and Guatemala share a border, the guerrillas operating in those countries share little, other than a similar leftist ideology. Salvadoran guerrilla groups are media-conscious, broadcasting their communiques from clandestine radio stations and routinely receiving journalists for interviews. To their countrymen, the guerrillas are known as los muchachos, the boys.

The EGP in Guatemala is another creature. It is a secretive group that, during its two decades of activity, has been periodically pummeled by the Guatemalan army, an efficient military machine trained in Israeli and Argentine counterinsurgency techniques. An interview with the guerrillas would be a good story.

A guerrilla spokesman told Blake's younger brothers that Nick had approached the EGP in Nicaragua about interviewing the rebel woman, but that the EGP had said it could not arrange anything. The guerrillas said they might risk the arrangement if Blake represented a television network.

Blake decided to go ahead with his plans, following the rules of the road that he had learned in El Salvador. "I think Nick just got fed up and said, 'Dammit, I'm going in there,' " said Sam, 24, a graduate student of law and diplomacy at Tufts University near Boston. "I think it was a miscalculation."

In Guatemala, Blake met Griffith Davis, a resident of Guatemala for eight years. Davis had settled in the picturesque village of Santiago Atitlan after journeying overseas in the years following his graduation from Pennsylvania State University. He and his American girlfriend made handicrafts and sold them in nearby Panajachel, a town known as a hangout for 1960s American dropouts. Davis returned to the United States every year to visit his family in Scranton and to accumulate some money by picking apples in Vermont.

With Davis as guide and photographer, Blake left on March 25 from the city of Huehuetenango. The younger Blakes trailed the two to the town of El Llano in El Quiche province. The province is the heart of the area where the guerrillas and the army had been fighting.

In El Llano, Blake and Davis told the military commanders that they wanted to go to Sumal, a day's hike away. The army advised against it. The Americans went anyway. That was the last place they were seen.

*

The Blake brothers' early investigation led them to believe that the army had kidnapped Blake and Davis. Guatemalan officials, they said, were uncooperative. A guerrilla official they met in Mexico City denied that the EGP had even seen the two men. The U.S. Embassy's explanations, the brothers said, seemed designed to benefit the military regime.

"The embassy started out real suspicious," said Sam Blake. "They just seemed to be pawning it all off on the guerrillas without checking it out."

The embassy, Sam figured, was "the only tool we (could) use to bash the army." He said that family members contacted their congressmen, and that "a bunch of big shots in Washington" sent cables to pressure U.S. Ambassador Alberto Piedra to step up the investigation. Sam contacted his professors at school to do the same.

Through a family friend, the Blakes asked Vice President Bush to intercede. Bush, Sam explained, "lives about 10 minutes from us" in Maine, where the Blake family spends its summers.

"The embassy finally got off their duffs and did some things," said Randy Blake, 25, an aide in the Washington office of U.S. Rep. Bob Edgar (D., Pa.).

Embassy officials in Guatemala City said they dropped leaflets from a helicopter a couple of weeks after the disappearances and urged the Guatemalan military to look for the two.

"I don't think the Blake brothers appreciated the work we did," said a State Department official in Washington.

The brothers didn't trust the embassy. Last fall, their inquiries became more combative. In November, during a presidential election that returned the power in Guatemala to a civilian government, Randy and Sam flew to the capital to hold news conferences suggesting that the military had kidnapped their brother. They scaled a fence in Guatemala City to join the Mutual Support Group, an organization that had seized the the country's cathedral to draw attention to their calls for an investigation into mass disappearances of Guatemalans.

*

While the brothers were holding news conferences, Mary Blake remained in Philadelphia.

Mrs. Blake, who visited Guatemala last April after her oldest son disappeared, said she had information that led her to believe that Nick was alive, but she would not say what it was.

"I've always proceeded from the point of view that he's alive," she said. "As long as there's a chance that he's alive - a hope - I have to do that. My sons proceeded from the assumption that he was dead."

The Blake brothers said the divisions with their parents also stemmed from their different political points of view. The three sons considered themselves liberal Democrats, while Mary and Richard Blake, who works at First Pennsylvania Bank & Trust, "are staunch Republicans" who are more inclined to believe the government, Sam said.

The sons' beliefs, however, changed to align more closely with their parents' views after Sam's third trip to Guatemala last month.

Sam met the witness who was supposed to have seen the army cart away two gringos in a helicopter. The story Sam heard was not remotely like that, and he dismissed it as groundless.

He also met with the new civilian president, Vinicio Cerezo. The president told the military to cooperate with Sam. The army commanders showed him their intelligence reports and activity logs from last April. They flew him into the area where his brother and Davis disappeared. He interviewed men at the garrison near El Llano.

The army's story - that the Americans had gone into the countryside despite its warnings that the area was crawling with guerrillas - rang true, Sam said. "Just going up there, I realized the army wasn't in control of the area," he said, which is what the Guatemalan military and the U.S. Embassy had been saying all along.

"I think we've exhausted everything against the army, and I think we should say we were wrong," he said.

That does not mean the Blakes are going to apologize for everything they said before. "They seemed pretty honest," Sam said of the military. "I've got to admit, those guys are pretty sleazy when it comes to Guatemalans. But when it comes to Americans, they just don't take them."

And as for the embassy officials in Guatemala City, he said, "Maybe we shouldn't have been so confrontational with them. . . . They're pretty despicable, but I don't think they're going to tell us lies for six months."

That leaves the question of what happened to Nick Blake and Griffith Davis. "My parents don't want to come close to the possibility that he's dead, and Randy and I accept it," said Sam.

There seems to be only one plausible scenario in which the two would be alive - if they have joined the guerrillas. The highly mobile insurgents, as well as the army, are not known for keeping prisoners. They are excess baggage in irregular warfare.

But the Blakes and Dolores Davis, Griffith's mother, said the hikers were unlikely recruits for the guerrillas. While they were sympathetic to the social unrest that caused thousands of peasants to join the insurgency, neither was known to have strong political views.

Randy and Sam Blake said they are turning their attention to the Guerrilla Army of the Poor, whose officials, they said, were circumspect and reluctant to help their investigation.

"Maybe excessive doctrinaire thinking got in our way," said Sam. "I mean, we're liberals and, you know, the army down there is one of the worst in the world for human rights violations. But maybe we ought to start rethinking this case."

U.S. officials say only that the investigation is "ongoing."

"I get calls now and then from the State Department," said Dolores Davis. But the incident seems so foreign to her, so dreamlike. "The State Department is talking about places they went to, towns, you know. I can't even pronounce the names of the towns."

The incident has brought home the emotional torment that thousands of Guatemalan families experience, the families that have no body and few clues as to what happened to their loved ones.

"Not knowing is hard," said Dolores Davis. "This could go on forever."