Slogging through the moors with Jane Seymour isn't everyone's idea of gripping entertainment. But "Jamaica Inn," a four-hour mini-series based on Daphne du Maurier's gothic tale of romance and evil, is a brooding, taut mystery -- well worth it for televisionados who don't mind sinking mindlessly into two dark and stormy nights.

Airing tomorrow and Monday on Channel 5 (8 to 10 p.m.), "Jamaica Inn" boasts a fine cast, headed by Seymour, whose exquisitely chiseled features compete with the Cornwall coast for Best Visual Effects. No Meryl Streep in the Sturm und Drang department, and at times looking like a promo for Laura Ashley or Ralph Lauren, she gives a spirited performance as Mary Yellan, du Maurier's wide-eyed heroine who stumbles upon the evil men do. As a result, she is the better for it, risking a life of high adventure over the security she seems to need.

Fans of "Miami Vice" take note: This is pretty tame stuff. No sex. Tasteful violence. And the only coke is the stuff ye olde bog-dwellers burn as fuel.

The opening scene sets the tone for this foggy tale (filmed unsuccessfully by Alfred Hitchcock in 1939) as a sailing ship rounds the rocky English coast. "Aye, it's a darty night," a crewman mutters. On the shore, a roving band of "wreckers" are up to no good. They stab the lighthouse keeper to death and ignite their own torch, guiding the ship to the treacherous shoals and its crewmen to their watery graves.

They board the ship, pillage and plunder, and with not even a yo-ho-ho disband into the night.

Among the dead is Mary's father. She and her mother, Martha (Vivian Pickles), are devastated, and the latter dies of grief. Mary is sent to live with her Aunt Patience (Billie Whitelaw), now married to the drunken Joss Merlyn (Patrick McGoohan), the proprietor of Jamaica Inn.

As the cymbals clash and the drums roll out their warning, Mary makes her way across the countryside to the dreaded destination. "Even the horses don't like stopping there," the driver says. "He's right, Missy," a woman traveler offers. "If I was you, I'd give up any thought of going to Jamaica Inn."

Obviously, Mary didn't consult her travel agent. Greeted by a pack of growling dogs and an innkeeper who makes Lon Chaney look like Conrad Hilton, she is escorted to a room where the rats have already checked in.

"Welcome," Uncle Joss snarls, two-day-old drool on his chin. McGoohan gives a rousing performance as the evil innkeeper and host to the band of smugglers, throat-slitters and social misfits who frequent his roadside establishment.

The once-spirited Aunt Patience looks like the "before" picture for Grecian Formula -- her hair is white, her eyes buggy with fright.

"Don't be afraid," she tells her niece. "There are things that happen at Jamaica Inn, Mary. Bad things. Evil things. I can't tell you. I can't even admit them to myself."

Naturally, Mary starts snooping around and discovers that her uncle, as leader of the horrible "wreckers," is a one-man Bermuda Triangle.

Meanwhile, she has taken a fancy to Joss' brother, Jem (Trevor Eve), a dashing horse thief who has a considerable amount of roguish charm. "We Merlyns have never been good to our women," he says, thus cementing the relationship.

There are genuine sparks between Seymour and her stubble-chinned love interest, and it's a relief to see the actress opposite a real, scruffy man, not a cardboard replica of her own asymmetrical beauty.

John McEnery does a neat job as the mysterious vicar, the Rev. Francis Davey, the one man Mary comes to trust.

You know the production is at least making a stab at authenticity by the straw on the floor and the fingerless gloves the players wear. And there are plenty of hounds and horses, carriages on cobblestones, and everybody drops their h's. (Mary: "I've risked ev'rythin' ta cumm 'ere.")

When the malicious Joss and his wife Patience are brutally murdered, Mary's life hangs in the balance.

"You were the rock, Mary Yellan, against which we ran aground," the killer whispers. "With your wide inquiring eyes you came amongst us and I knew then the end was near."

Some viewers may wish check-out time came sooner. There's plenty of room in "Jamaica Inn" for improvement, but any reservations should be dispelled at the sight of Seymour's scene-stealing kisser.

Even if she does wear a wee bit too much Jamaic-up.