HBO (Sat, July 12, 11:30 p.m. ET)

B+

While no one would expect a drama set in a place called Oswald Maximum Security Penitentiary to be a frolic, some viewers may be repelled by the sheer concentration of ugliness in this eight-episode series from executive producers Tom Fontana and Barry Levinson (Homicide: Life on the Street). The July 12 premiere starts with an inmate being stabbed and ends with one being set on fire. In between there's nary a ray of sunshine. But the Big House is filled with fine actors, including Ernie Hudson as the businesslike warden, Terry Kinney as the intense, idealistic head of an experimental unit that stresses rehabilitation, Eamonn Walker as a Muslim prisoner who combines militancy and serenity, Jon Seda as a young Mafia hothead, Lee Tergesen as a babe-in-the-woods lawyer sentenced for killing a child in a drunk-driving incident, and J.K. Simmons as his predatory neo-Nazi cellmate.

By the second episode (July 14 at 11 p.m.), you may be wearying of the disabled prisoner (Harold Perrineau), who delivers pretentiously hip commentaries to the camera, or disgusted by the Jeffrey Dahmer-like parent-killer (Sean Whitesell), whose unnatural appetite is apparently writer Fontana's idea of a good sick joke. But you won't escape easily from this drama's grip.

Showtime (Sun., July 13, 10 p.m. ET)

B

Though it's not of the same caliber as ABC's Gun, a similar series that had a short springtime run, this anthology promises to keep viewers reasonably entertained as it follows a gun from owner to owner in the Old West. Launched as a trilogy in March, it returns with two back-to-back episodes on July 13 before moving to its regular Wednesday slot (also at 10 p.m.) starting on July 16.

The first July 13 episode is the sweet, mostly comic tale of a mild-mannered peddler (perfectly played by executive producer Henry Winkler) who impersonates a feared lawman and manages to tame an unruly town by being nice, saying little and packing an impressive firearm. In the second July 13 story, Larry Drake (L.A. Law) has an eye-rolling good time with the part of an undertaker who loots the possessions of the deceased and practices his oily charm on their widows. The story falters, though, when it switches from sardonic humor to graveyard fright after Drake shoots his equally greedy partner (Ken Pogue). Drake seems too smug to be freaked out by a murdered man's ghost. He would be more likely to charge him a reburial fee.

Fox (Mondays, 9 p.m. ET)

C+

Here's a series that lives up to its name. Set at the dawn of the 5th century on the isle now known as Ireland (but filmed in Australia, where skies are incongruously sunny), it features clangorous combat scenes in which warriors emit fierce, throaty sounds while having at one another with swords, spears and fists. Your only defense: turn down the volume.

Heath Ledger, a fresh face from Down Under, plays Conor, the reluctant hero drafted by destiny to unite the fractious Celtic tribes in opposition to the Roman Empire. Though Ledger seems steady enough as an actor, there are signs in the July 14 premiere that 20-year-old Conor is in over his head, so he's lucky to have a tough but likable bodyguard in Fergus (John Saint Ryan, who bears a distinct resemblance to Sean Connery). They will have to contend with evil Queen Diana (Lisa Zane) and her 400-year-old sorcerer-adviser, Longinus (Sebastian Roche). But our money is on Ledger's legion of vigorous underdogs, who roar with pride when he hails them as people who "will never be silenced." Yeah, so we've heard.