Ask Nan Davis about her first encounter with Dr. Jerrold Petrofsky, and the answer comes so quickly and easily it's like asking what date Christmas falls on.

"It was June 7, 1982," she said. "I met him in Minnesota at a spinal cord injury convention. I wasn't going to bug him about getting into his program. But I went up to talk to him about it and he said, 'If you're interested, give my assistant a call.'

Four days later Nan Davis was in the program. And, with Petrofsky, she found herself on the cutting edge of research offering the hope of improved lives to victims of spinal cord injuries. Not a quick cure, but hope.

Their story -- two stories, really -- come to television Tuesday night in "First Steps" on CBS.

His is the story of a research bio- engineer working on computer-driven devices to stimulate paralyzed leg muscles of paraplegics.

Hers is the story of a woman who was a passenger in a car that left the road on the night of her high school graduation in 1978. The accident left her paralyzed and sent her through a cycle of emotions that ranged from depression to bitterness.

Their stories came together that day in Minnesota. The results of their collaboration -- which included her taking 10 machine-aided steps to receive her college diploma in 1982 -- have been the subject of "60 Minutes" segments three times and the "Donahue" show twice.

Now it's a drama, with Amy Steel playing Davis, and Judd Hirsch as Petrofsky.

"I thought they did a good job," said Davis of the production. "I was surprised how accurately they did the technical stuff in the lab. They were very technically accurate. They realized that if things weren't accurate, it might raise false hopes."

Davis works in Petrofsky's laboratory at Wright Sate Univrsity in Dayton, Ohio, 60 miles from her home town of St. Mary's. Each day she pedals a bicycle for half an hour, her muscles stimulated in proper sequence by computerized electrodes attached to her legs. The idea is to keep her muscles toned and to stimulate Davis' cardiovascular system.

She and three others spend about two hours a day in a walking system that affords physical support plus electrical stimulation.

A lot of work remains to be done, she said, before such a system becomes practical for general use. And there are other researchers working to develop ways of treating the incredibly delicate spine itself.

A mass-audience drama on the subject might stimulate contributions to the programs. "I hope so," said Davis. "The show does a couple of things. It gives an idea of what the injured person and a family goes through. And it says that this is happening out there -- our research and the research on the spinal cord itself.

"We don't claim to have a cure. It's something to keep people fit and ready if and when a cure comes."

For a time, there was talk of making Davis the star of her own story. But technical problems and emotions got in the way.

"The producer at first wanted me to play myself," she recalled. "I tested for it. But I'm glad I didn't. It was easier on me not to."

Had she played the part, Petrofsky's equipment would have had to be taken to Chicago, where the filming was done. Steel used non-functioning mockups.

And Davis would have been forced to relive all the feelings that come with sudden disability.

"The feelings they bring out in the film," she said, "I've tried to block out for years."

Davis is still only 24. She has time to wait for the research to catch up with her.

"I really don't know what lies ahead," she said. "I don't want to try to estimate. I'll take it as it comes. Even if it just meant the development of something for use around the house -- to help you get something down of the top shelf -- that would be fine."