Rep. Gus Savage got the call around midnight.

It was his 25-year-old son, "Little Gus," telephoning from Precinct House 5D in Northeast Washington where he was being held for driving without a license and driving an unregistered car.In minutes, Big Gus Savage, a freshman Democrat from Chicago's South Side, was on the case.

He talked his way to the top of the precinct hierarchy. No one could help.

He called the U.S Capitol Police. They couldn't help.

He called D.C. Police Chief Burtell M. Jefferson. He helped.

By the time Jefferson's call reached the station clerk at 5D, the arresting officer had filed a preliminary record of the arrest and submitted it for booking. Within minutes, the officer was told to stop the paperwork, an inspector had arrived from police headquarters to take charge of the situation, half a dozen police officers who took part in the arrest and booking were ordered to write reports of their actions for the chief.

And, less than two hours after he had been taken into custody at 18th and Benning Road NE, Little was Gus released without posting the normal $50 deposit, which is usually refunded once police see the license.

It had all the makings of the classic Washington Connection in action.But yesterday afternoon, Gus Savage, a self-styled reform politician, wasn't worried about special influence. He said he was shocked at the discourteous treatment he had received, the slow police response to his calls and Mayor Marion Barry's failure to prompty return Savage's midmorning call. An aide Barry might return the call today.

To make matters worse, a D.C. police lieutenant had telephoned moments earlier to inform Savage that the case was under investigation; Little Gus might still be charged. Savage said he took that as a threat to not talk with the press. Big Gus is not a man known to hold his tongue:

"I have always supported home rule for D.C.," he said, "but I want it known that because of this kind of irresponsibility there is one black member [of Congress] who is against home rule. You cannot have a city where the most prominent public comes into such irresponsible hands.

"I think he [Barry] would have enough control over this police department if he is a competent mayor," Savage fumed, adding that in his opinion, the department is racist, even though the chief, whom Savage acknowledged as helpful, and most of his commanders are black. "I do not believe they would have treated a white congressman that way."

The police "rejected the ID my son carried signed by me. My son was dressed in a suit, shirt and tie. He doesn't have a beard. He's a normal looking student. They held him two hours," Savage said. Savage said a female officer was rude to him and told him he would have to come to the station if he wanted his son released.

"I said it was 1 a.m. I have a committee meeting at 8:30. She said that was too bad. I asked for the night commander. She couldn't find him. I said could I talk to anybody and she said no, I'd have to come to the station," Savage said. He said he finally asked to speak to the highest ranking person there, a sergeant, but the voice on the other end of the line said the sergeant was too busy.

"How can some sergeant refuse to come to the phone?"

Savage did not dispute the official police account that his son was stopped because the 1980 black Oldsmobile did not have license tags. Police took his son into custody after he could not produce a driver's permit or the car's registration.

Savage said the car had just been driven from Chicago Wednesday night by an aide who brought it to a Southwest Washington restaurant where Savage was dining with his son and others. The son left the restaurant to take the friend home, forgetting that his driver's permit was at home, Savage said. But he said his son had identified himself to police with a card issued by the House of Representatives to members of congressional families.

Moreover, Savage said, there was a sticker issued by Illinois authorities attached to the front windshield of the car indicating that it was "in transit" and could be temporarily driven without tags.

Early yesterday, a police spokesman said such a sticker was meaningless on the streets of Washington. Later, however, Assistant Chief Maurice T. Turner said police would recognize the sticker, and that the son holds a valid driver's permit from Illinois. A warning would be issued, but no charges filed, Turner said.

Rep. Savage said he gladly would have gone to the station house to help get his son released. But, "I didn't have a car . . . They had my car. You can't get a cab. I pay $950 a month rent. I have a decent suit and I have trouble getting a cab to stop for a black [man] in the day, let alone 1 o'clock in the morning."

Savage said it was only after he was rebuffed that he called the higher-ups.

According to police at the station, Savage's calls interrupted what they thought was a normal traffic case. The arresting officer was filing out routine forms and running the son's name though the police computer, a standard task in any arrest. Officers said the son was polite, coorperative and even appeared hesitant to call his father. He asked no favors.

"They treated me rather well," said young Savage.

A short while after the son called his father, a high-ranking official of the Capitol police telephoned. The official, Inspector Alan Bowers, had been called by Savage. Capitol police said Bowers determined he couldn't help the situation and suggested that Savage call Jefferson.

A few minutes later, Jefferson was on the phone to a precinct lieutenant. Jefferson, who refused yesterday to discuss his actions, told the lieutenant to release Savage and later ordered Inspector Joyce Leland, the highest ranking official on duty Wednesday night, to go to the station to investigate how Savage's arrest had occurred, sources familiar with the incident said.

Leland, who also was unavailable for comment, told the six officers present after Savage left to write detailed statements on what had happened, the sources said. The statements were not made public.

A police spokesman said yesterday that the officers who released Savage without writing traffic tickets had misunderstood Jefferson's order. Lt. Hiram Brewton said Jefferson had intended for the officers to write tickets but not keep Savage overnight. Officers yesterday sharply disputed that account.

Larry Melton, vice president of the police officer's union, said the arrest was "done in the normal fashion" and said "the union is monitoring the situation to make sure the officers are not made scapegoats."

Rep. Savage, who divested himself of several weekly newspapers in the South Side of Chicago after he was elected to Congress in November, has a reputation as a gutsy fighter who opposed machine politics for more than three decades.

Savage's son, who is new to Washington's fishbowl politics, was somewhat confused yesterday by the swirl of attention the case has received. He pointed out to a reporter that he prefers to be called by his given name, Thomas, instead of Little Gus, as many of his friends dub him.

"You know you always want your own identity," Little Gus said. "I'm sorry I had to get it this way."