With "Dallas" in summer reruns and President Reagan and Congress on vacation, the biggest show in Texas this month is a true-life soap opera called "Who Shot Mike Martin?"

Texans aren't normally embarrassed by tall tales, but this one, which has dominated state newspapers all month, has made even the natives blush.

"In the 135 years of Texas statehood, there have been many strange events in Austin involving members of the august Texas Legislature," the Dallas Times-Herald said on Sunday. "There have been 'Killer Bees' and even a few dead men appointed to public office. But perhaps nothing that has ever happened in the Texas capital was quite as bizarre as the recent shooting of Rep. Michael W. Martin."

Mike Martin had himself shot, police now believe, but that is giving away the punch line a little early, even though the tale isn't nearly that simple, and it's useful to know a little background on Martin before getting to the "facts" of this case.

Martin, 29, was a carpenter before he got into politics. But he told a Texas political reporter earlier this year, "Don't compare me to another carpenter, please. They crucified Him."

Last year, he ran for the state House of Representatives as a Republican. He campaigned on a variety of right-wing issues, knocked on virtually every door in his East Texas district and upset his Democratic opponent, in part because Ronald Reagan got 68 percent of the vote in Martin's home county. After the election, Martin reportedly was surprised to learn he had to wait two months before taking office in Austin.

The man Martin defeated was a committee chairman, and so when Martin arrived at the legislature, he politely told the committee staff he wouldn't need their services. So unschooled was Martin in the ways of a legislature that he apparently believed that by defeating a committee chairman, he could take over the committee, even though the Democrats hold a 2-to-1 edge in the state house.

Martin, a devout Christian, had only one mission in the legislature during this year's session, and that was the passage of a bill to require the teaching of creationist theory wherever evolution is taught. But he was so untutored in the parliamentary process that he forfeited any real chance of having his bill taken seriously. At the end of the season in June, he was named one of the state's 10 worst legislators by Texas Monthly magazine.

That might have been the end of the Mike Martin saga, had he not aspired to higher office. The Democratic state senator from his district is thinking of running for governor in 1982, and Martin decided he should run for the possibly vacant seat. So began the soap opera.

Sometimes after 2 a.m. on the morning of July 31, Martin arrived back at the trailer park where he lives while in Austin. (The legislature was in special session at the time.) He said he got out of his car, raised his left arm, and in an instant had been hit by at least three .00 buckshot pellets from a 12-gauge shotgun. He said he hit the ground, while the gunman peppered his car, which includes a bumper sticker that reads, "I am bound for the Promised Land," leaving 17 nickel-sized holes on the passenger side.

Martin was found bleeding in the front seat of his car by an associate. It appeared Martin's life had been saved by his left arm, which he had raised, he later said, (a) to look at his watch; (b) to stretch and yawn; or (c) to protect himself from an assailant he noticed as he stepped from the car.

But we're getting ahead of ourselves here; the inconsistencies didn't become obvious until later. Martin handed his associate a list of people to call in the event of such an emergency. It did not include the police or an ambulance, but did name Martin's PR man. That didn't come out until later, either.

At the time, the shooting was no laughing matter, especially after the attempted assassinations of President Reagan and Pope John Paul II, and Martin basked in sympathetic publicity as investigators searched for clues.

Martin said he had no idea why he was shot, but suggested it might have something to do with an investigation of construction bidding irregularities in his home county. Political supporters suggested it was retaliation for Martin's attacks on big government.

Martin told reporters he had been receiving harassing phone calls in the weeks before the shooting and had feared for his safety. "I won't lie to you," he said a few days after the shooting. "I'm a little scared right now. Whoever did this was pretty sharp about not leaving any clues."

The next week, Martin failed to respond to a subpoena from a grand jury looking into the shooting. He said police had not guaranteed him protection. (Authorities said he had never asked about protection.) His PR man, Leslie Smith, put out the word: "The last place in the world Mike Martin wants to be now is in Austin, Texas. There's a madman out there trying to kill the kid."

Skeptical police continued to search for clues and untangle the inconsistencies in Martin's own story, but the freshman Republican soon provided his own answer to the case. His assailants, he told friends, were members of a Satanic cult, the Guardian Angels of the Underworld, who feared he would expose them and had been threatening him and his wife on the telephone.

Even his closest associates gagged on that one and bailed out on him publicly. Martin ignored another grand jury subpoena and went into hiding, while investigators closed in. Meanwhile, his mother announced that Martin denied he had blamed the shooting on the Guardians of the Underworld.

Late last week, Martin's world came crashing down when his first cousin, Charles Goff, told police that he and Martin had staged the whole event to advance Martin's political career. Police found Martin hiding in a stereo speaker cabinet at his mother's house in Longview. The Republican legislator called his cousin a liar, and apparently told the grand jury -- when he finally appeared before it on Tuesday -- much the same thing. He now blames the shooting on a political conspiracy in his home county.