Grace Gardner is still willing to interface with Sgt. Esterhaus any time and any place, even if he sees other women. "Sharing you doesn't diminish me," she says nobly. "There's so much of you to share."

Capt. Frank Furillo and public defender Joyce Davenport are still trying to work out the parameters of their relationship -- "either we move forward, or it's over," Frank says -- but Frank's ex-wife is still dropping by, as she does when he turns 40: "Do you remember," she asks him purringly, "that little something extra I used to give you for your birthday?"

Mad Howard Hunter is still dogging what he calls "miscreants" with eternal vigilance and extreme prejudice, and undercover man Mick Belker is still hauling suspects into the hoosegow with intimidating rhetorical queries like, "Do you wanna sit down, dog-breath, or would you prefer a collapsed lung?"

When Belker arrests an orangutan for purse-snatching and grows attached to it, and Furillo suggests putting the ape in the detention room, Belker asks incredulously, "With those animals?"

NBC's "Hill Street Blues" is back -- at 10 tonight on Channel 4 -- and if not better than ever, at least as good as ever, which is better than anything else on any network's schedule right now. By several long shots. The second season of the brilliantly brittle and dazzlingly hyper-active police series finds the Hill Street irregulars once more struggling for balance on the Tilt-A-Whirl of life. The big city has never been bigger than in this tough and ambitious fugue for flatfeet.

There were indications before the season began that "Hill Street" would be compromised in order to attract larger audiences. The program has always been full of surprises, which allegedly upset home audiences; after all, television had spent 30-some years not surprising them as often as possible. But if there has been streamlining, it is not ruinous or treasonous. One plot line is supposed to be wrapped up each week as part of the remodeling; tonight, a search for a 7-year-old boy ends when the boy is found. Just as well.

In what may be, semantically at least, a television first, it is stated that a cop is under suspicion of having lured a topless waitress into his car and telling her that, to quote the script, "if she didn't fellate him, he'd arrest her." There is a lot of talk about sex on "Hill Street Blues," but it isn't smarmily titillating. It's adult.

The cast remains cheerable, especially Daniel J. Travanti (Furillo), Barbara Babcock (Grace Gardner), Michael Conrad (Sgt. Esterhaus), Charles Haid (Renko), Michael Warren (Hill) and Bruce Weitz (Belker, wolf-man among men). The script and direction, under the supervision of series creators Steven Bochco and Michael Kozoll, are beyond anything done before in series television -- even "M*A*S*H," which is supposed to be such a model of cynical sophistication but which looks like "Happy Days" by comparison.

When hysterics suddenly break out in the station tonight, and shots are fired, and a man falls over in a bloody heap, you know that it wouldn't happen just this way on any other television show but that it could very well happen just this way in life. "Hill Street Blues" has returned in tumultuous triumph.