On Oct. 24, Leslie Hughes, a 28-year-old housewife in suburban Rochester, N.Y., took her two children to a neighborhood McDonald's. That night, troubled by the Playmobil toys they received with their "Happy Meal" orders of hamburgers, french fries and soft drinks, she called the head of a local consumer group.

Eight days later, on Nov. 1, McDonald's Corp. voluntarily recalled 10 million of the toys and canceled an expensive promotion -- all because of the chain of events set off by that one phone call.

Nobody had been injured by the plastic figures of gun-wielding sheriffs or spear-carrying Indians; there had been no costly damage suits or harmful publicity. But for a major corporation as dependent on public good will as McDonald's, the mere possibility of a major public controversy was enough to make it move quickly to cut its losses.

The recall was a testament, in a sense, to the sophistication and power of a relatively small group of consumers and the ends even the biggest company will go to in protecting its image in an age when a Tylenol contamination can have a devastating impact literally overnight.

"This case illustrates the maturity of the consumer movement," Ralph Nader said yesterday. And, he said, it shows the effectiveness of "knowledgeable consumers who know how to invoke the safeguards in federal consumer laws."

To Nancy Harvey Steorts, chairman of the U.S. Consumer Product Safety Commission, which tested the toys in response to Hughes' concern and found that they could be dangerous to small children under the age of 3, the voluntary recall by McDonald's "epitomizes industry cooperation."

"They came in and worked out a solution; they recalled the product," she said. "I only wish other companies were as cooperative as McDonald's."

Officials at McDonald's headquarters in Oak Brook, Ill., said they acted as soon as they recognized that the toys had failed federal tests and posed a potential problem. "We said to CPSC that we think this -- withdraw the toys -- is what we should do," said Richard G. Starman, assistant vice president of communications.

"I think they were surprised," he said. "Their reaction was, 'Really?' "

All this might not have happened if Leslie and William Hughes hadn't spent all day Sunday, Oct. 24, on a family outing and decided to end it by driving by their local McDonald's to buy dinner for their two daughters, Katy, 3 1/2, and Lindsay, 1.

"We took the 'Happy Meals' home and sat the kids at the table," Mrs. Hughes said. "And after they finished, I took the toys out of the box and I couldn't believe it. The rifle was so small that my daughter could have put it in her ear or her nose or her mouth. My husband and I agreed that these weren't for small children. It really surprised me that McDonald's would give these things out."

Mrs. Hughes, a member of the Empire State Consumer Association, a consumer group in the Rochester area, decided to call Judy Braiman-Lipson, a friend who is president of the consumer group. Braiman-Lipson took it from there.

"I went to McDonald's that same night and purchased a 'Happy Meal' with the toy," Braiman-Lipson said. She took the toy home and conducted her own test of the rifle by trying to insert it into a cylinder that replicates a child's throat. Her cylinder is identical to the one used by government researchers when they test toy parts to determine if there is a choking hazard for small children.

"The rifle didn't fit, but just barely," she said.

The next day, Braiman-Lipson called a McDonald's representative in Rochester to express concern about the Playmobil toys. The call was referred to Steve Leroy, a public relations representative in the company's Oak Brook headquarters.

Leroy talked to Braiman-Lipson and agreed to arrange for a conference telephone call on Oct. 26 with three McDonald's officials in Oak Brook and a representative of the United States Testing Co. in Hoboken, N.J., which tested the toys for McDonald's in January -- before the promotion and giveaways started -- and found that they passed or exceeded all federal standards for small toy parts.

In the meantime, Braiman-Lipson had also called the U.S. Consumer Product Safety Commission in Washington.So,on the morning of Oct. 26, as the Rochester women and the McDonald's officials began their telephone conversation, CPSC Inspector Richard D. Early arrived at the McDonald's restaurant in the Mazza Gallerie Mall in Northwest Washington and asked for samples of the giveaway toys.

McDonald's then telephoned the CPSC office in Washington to offer its full cooperation and learned that a Chicago-based CPSC representative, Bruno Slivinskas, was being dispatched to pick up more toy samples from the Oak Brook office.

David Smeltzer, director of compliance for CPSC, said the first parcel of toys arrived Oct. 28, and the laboratory researcher began preparations to test the small toy parts. The procedures included a tension test to determine if a child aged three years or under could break off the arms or legs. If they could be broken off, the appendages then were inserted into the cylinder that is the size of a small child's throat. If the appendage could fit into the cylinder, the toy fails the test.

By 3:30 p.m. last Friday, the preliminary results were in.

"Three toys failed," Smeltzer said. He telephoned John Horwitz, one of McDonald's lawyers, to tell him of the results and to say that more tests of the remaining toys would be conducted over the weekend.

In the meantime, McDonald's officials had asked United States Testing Co. to conduct new tests of the Playmobil toys to determine if there was a problem. "We got our initial responses results on Sunday," Starman said. "We started getting reports verbally from the lab that they the toy arms and legs were breaking" and failing the test.

What isn't clear is why the toys passed the tests in January and failed this past weekend. United States Testing Co. officials would not comment when asked about the disparity in their test results.

A meeting of 20 McDonald's executives was called last Sunday night, Halloween, in a conference room in the main Oak Brook offices.

At 11 p.m., after meeting for four hours, company officials placed a call to CPSC Chairman Steorts at her home and arranged a meeting for the next morning in Washington.

At the meeting, Smeltzer revealed the final results of the toy test: 25 to 40 percent of the 60 toys tested had failed the standard because the appendages broke off too easily and posed a choking hazard. The rifles, however, passed the test.

At noon, officials from Schaper Manufacturing Co., the Minneapolis-based company that made the Playmobil toys, arrived. Among other things, they suggested that the McDonald's giveaway could be continued if the toys were labeled with a warning that they were suitable only for children aged four or older.

"We weren't enthusiastic, because we don't want to distribute anything that may be appropriate for some children and inappropriate for other children," said Starman, who said Schaper had contracted to make a toy suitable for children of all ages.

A recess was called and the McDonald's team made its decision: withdraw all the toys immediately.

They told the CPSC what they intended to do and outlined a plan of implementation. At 6:15 p.m. Starman and the others made a conference call to Oak Brook and asked that the company's 26 regional managers be instructed to stop the giveaways and remove the promotional material from the stores.

By midnight, the orders had been carried out.