Fire Captain Thomas Moody never should have been at the World Trade Center that day.

The 45-year-old Stony Brook man had been doing desk work for months, developing a course to teach other firefighters how to handle hazardous materials.

But on Sept. 11 he was asked to help fill in for some firefighters who needed to take physical examinations.

The company that Moody was filling in with, Hazardous Materials Operations, was called to the World Trade Center at about 9 a.m.

Neither Moody nor any of the 17 men he was with that day have been heard from since.

Moody's wife, Maureen, and four children, Jessica, 12, Erin, 11, Sean, 8, and Deirdre, 6, are still waiting for facts about what happened to him.

"I don't even know what to pray for anymore," his wife said.

Born in Queens and raised in Brentwood, Moody comes from a family of firefighters. His father, Charles, and uncle, William, were both New York City firefighters. They passed their tradition down to Thomas and his brothers, Frank and Michael, all of whom joined the New York City Fire Department.

"He just loved the firehouse," Maureen Moody said. "It really is like a brotherhood."

Moody has put himself on the line to help people before. He fought the Lefrak City fire in Queens in 1989 and, despite some injuries, made it to the birth of his first child, Jessica, several hours later. He also responded to the first terrorist attack at the World Trade Center in 1993.

Friends say Moody is so quiet that they're surprised he got up the nerve to ask his wife out on their first date in 1984.

Yet they say he also has a sense of adventure - one that led him to go skydiving and ride motorcycles as a young man, and that allowed him to rush into danger to save lives later.

"He's levelheaded, but he likes to enjoy life," his wife said.

He is also very studious, in a quiet, modest way, family members said. He has a bachelor of science degree from SUNY Buffalo, and a professional engineering certification from the state. He also teaches fire technology at Suffolk Community College.

It has been important to Moody to have his family around him. His mother lives around the corner from him, and his sister, Loraine Butcher, and brother Frank live in the area as well. His brother Michael lives in Satellite Beach, Fla.

He is the kind of family man who always takes time to play games with his kids, during family get-togethers, family members said. Many winters he has his kids in the car with their sleds before the grass is even fully covered in snow.

The Saturday before the attack, Moody looked outside, saw the sunshine, and decided to rally his family for the summer's last beach trip.

On such occasions, neighborhood kids usually come out of the woodwork, with at least a few of the Moody kids bringing friends along.

But on this day, Moody wanted it to be just family.

"That's just the kind of guy he is," his wife said. "He saw that it was a beautiful day, and he wanted to take advantage of it.

"That was the best day," she said. "It was the last family outing we had."