An Atlanta businessman yesterday told in dramatic detail how he tried to pay off a $50,000 loan and wound up enmeshed in an alleged multimillion dollar overseas drug ring.

William Simon Coury, who has pleaded guilty to a felony in connection with the case, told a jury in U.S. court in Alexandria that a chance meeting with the alleged ring leader during Jimmy Carter's 1977 inauguration led him eventually to a bizarre role as a go-between who arranged shipment of tons of illicit drugs from India and Nepal to the United States.

Coury's testimony highlighted the opening day of the trial of the alleged ring leader, Donald David Haynie, and four others on a variety of charges related to the alleged smuggling operation, which is reputed to have made $52 million over the last six years.

Coury, who said his socializing with Haynie and others during the inauguration included a visit to Pisces, the Geortetown club, also described once being handed $8,000 in cash in a paper bag while he was being drawn into the ring's alleged operations.

Coury testified that he flew several times at Haynie's direction to and from New Delhi and Nepal to import hashish as repayment of the loan.

Coury, who uses crutches because of a bone disease, described the transfer of thousands of pounds of drugs to and from "stash houses" in Chicago, Boston and Florida and how he flew around the country with paper bags full of tens of thousands of dollars involved in drug transactions.

At one time, Coury said, he was held hostage in Haynie's West Palm Beach, Fla. home by Cuban drug dealers who said Haynie owed them money. On another occasion Coury, who pleaded guilty this month to one of eight counts against him, said he arrived at Haynie's Florida home to talk business and found several local "celebrities" there. He did not name any of the individuals.

Coury's three hours of testimony appeared to be central to the government's case which alleges that the five defendants imported more than 27,000 pounds of marijuana and a half-ton of hashish to the United States from Jan. 1, 1977 until last September.

Coury's involvement, sometimes with men identified to him by nicknames such as "The Fat Man," "Wedge" and "The Captain," ended last Dec. 5 when he and 11 others were arrested in connection with the seizure of 800 pounds of hashish in a raid at Dulles International Airport. Coury had arranged for the shipment, hopefully to pay off the loan, he testified, but was foiled by U.S. Customs Office agents who learned of Coury's plans.

In his opening argument, Assistant U.S. Attorney Henry Hudson outlined a chain of command from Haynie, also known as "The Captain," to underlings in charge of distributing drugs in Chicago, Boston and Florida.

According to Hudson, one of the men on trial, Jean Morrissette, was supervisor of "stash houses" in Florida, which Hudson said were single-family homes in secluded areas used as drug warehouses. Defendant Michael Vlcek was in charge of "stash houses" in Chicago, Hudson alleged.

Kenneth Lawrence Bates, who pleaded guilty yesterday morning to a charge interstate commerce in aid of racketeering, was the "stash house" supervisor in Boston, Hudson said.

Another defendant, Paul Max Jenkins, who arrived at court yesterday in a limousine, paid out and received money for drug transactions, Hudson said. Defendant Lynn Edward Fletcher helped shepherd customers at the "stash houses," according to the prosecutor.

Hudson said the men kept meticulous records, and allowed regular customers to back their trucks up to the "stash houses," pay cash and have their trucks loaded with drugs.

Coury, whose business was as a foreign trader broker with offices in Atlanta's Omni Hotel, was recruited by Haynie because of his business contacts in the Middle East and with customs officials, Hudson said.

Coury, who before testifying was saying a rosary in the back of the courtroom, said that during the Presidential Inaugural he met Haynie, who told Coury he was interested in investing in his business.

Eventually, Haynie agreed to loan Coury $50,000 as an investment, Coury testified. Bates handed him a paper bag containing $8,000. He was to receive the rest of the loan later, Coury testified.

Coury testified he told Haynie the money would be repaid either from a settlement from an automobile accident he had been in, or as a return on the investment.

"Haynie proposed an alternative method of payment," Coury said. "He asked me if I had an occasion in my travels to have seen hashish."

Haynie then told Coury he wanted him to import Nepalese Temple Balls, which is hashish made by Nepalese mountain people, Coury testified. His worldwide travels then began.