Pat and Gean Plaga were an hour into a poker game with two other couples at a rented cabin near Yellowstone National Park on Aug. 17, 1959, when things got a little livelier than they'd planned.

Twenty minutes before midnight, the walls started to shake, the lights began to flicker and poker chips, cards and cocktails suddenly slid from the table to the floor. A loud roar was heard outside as Gean, a coach at West High School, raced to the front door.

"He flung the door open and it was like a hurricane outside," recalls Pat. "Gean shouted, 'We've got to get out of here — now!' None of us knew what was going on, but we knew it wasn't good. We ran immediately to the car."

The Plagas and their friends didn't realize they were at ground zero of one of the most powerful earthquakes ever recorded in the United States. But they found out soon enough.

A tourist who was stopping traffic on the narrow highway above their cabin told them they'd have to wait in their car on a small plateau with several other motorists. "It's a quake," he said. "The road is blocked in both directions."

"We sat in the car in a rainstorm all night, with the ground shaking all around us," says Pat. "I cried and cried, thinking I'd never see my son again. He was 18 months old and I'd left him in Salt Lake with my sister so Gean and I could take a vacation. That night was the longest of my life."

As the sun rose, Pat wept for another reason: She was lucky to be alive.

The 7.5 quake in Montana's Madison River Canyon had triggered a massive landslide, sending 80 million tons of rock crashing down on campgrounds, the highway and into the river. Dozens of tourists were injured, hundreds were trapped and 28 people were killed. The land under Hebgen Lake had tilted upward, flooding cabins on the north shore with a wall of water and cracking the dam.

Miraculously, the dam held, but the damage was so immense that boulders blocked the flow of the Madison River, forming a new lake, later named Earthquake Lake.

On Aug. 17, the U.S. Forest Service will commemorate the 50th anniversary of the disaster at a visitors center that looks out on the destruction. But Pat Plaga doesn't plan to be there. "I've only been back once, and it was very unsettling," she says. "It's something you can never forget."

Pat, now 77 and living in Millcreek, met me for a Free Lunch of chicken salad and iced tea at Applebee's to recall the poker game that ended in a race to save lives.