"Prisoner: Cell Block H," the new late-evening series Channel 5 begins tonight, is an adult soap opera with all the subtlety of a fist in the mouth.

An Australian import (with the occasionally hard-to-understand accent), "Cell Block" promises us 30 minutes of violence, sex and hysteria weekday nights between 11 and 11:30 p.m. Just the thing to send you off to dreamland. n

The first episode introduces the women whose traumas provide the basis for the series. Most of the characters are familiar stereotypes from prison dramas past -- the sadistic guard, the kind guard, the waif who really didn't commit the crime she's in for, the violent lesbian, the sensitive husband killer, etc.

Although this program is hailed by its promoters as a "unique departure for late-night series television" because it marks the "first time a series has explored the subject of women in prison," it suffers from the usual problems of dramas that try to portray what life is like in prison.

The overwhelming characteristic of life in prison is boredom -- and of course boredom is not the stuff of exciting television. So instead we get an incident a minute -- in the first half hour alone there is an inmate suicide, a lesbian attack and two violent outbursts, an intentional burning of one inmate, a seduction of a visiting electrician, flashbacks of one character's murder of her husband, and portents of subplots to come. (There's at least one with nudity, if the snips of coming attractions are any indication.)

The acting is basic melodrama, with lots of head clutching and eye narrowing, cackles and grimaces. But in an on-going soap opera, broad strokes are often needed to differentiate the characters so the audience can keep them straight.

Considering its purpose -- an alternative to the evening news on the other channels -- "Prisoner: Cell Block H" could be a welcome diversion. But make sure the kids are asleep.