Open for lunch weekdays, 11 a.m. to 3 p.m.; for dinner Monday through Thursday, 5 to 10 p.m., Friday and Saturday, 5 to 11 p.m. AE, CB, D, MC, V. Reservations. Prices: At lunch, sandwiches $3.75 to $4.50, entrees $5 to $13.75. At dinner, main courses average $10 to $15. Theater menu weekdays 5 to 6 p.m., $7.25 to $11.75.

A good restaurant lurks in Charley's Crab, but it is constantly contending with the forces of mediocrity.

A half-level below the street at the Farragut North Metro station, Charley's seems a whole seafood department store, with high fashion and bargain basement, ready to outfit the plates of every member of the family for everyday or party, full of special events and sales promotions -- even its own newsletter. There is always the season's newest merchandise and often a blockbuster sale.

So you can take your pick. You could satisfy lunch nicely with a $5 mess of smelts, crisp and light. You could have a bucket of steamed mussels in buttery garlic broth in the lounge, perched on a bar stool. You could cozy up to a steamed lobster with a bottle of California white in a clubby nautical dining room, watched by stuffed seagulls and waitresses who are just learning to serve rather than hover.

But, like any department store, there are either gems among the schlock or schlock among the gems.

At lunchtime, gems predominate. This dozen-branch chain restaurant is too smart to lead with anything but its long suit, so take note of the blackboard at the entrance: It lists the fresh fish of the day. Depending on the fish, they can be charcoal-grilled (the best choice), broiled or poached in garlic butter broth. If you know nothing else about Charley's Crab, you should know which fish are available for charcoal grilling.

Some of the amenities come automatically: warm spicy rolls that are defrosted dough, crusted with salt, poppy sees and "secret" seasonings, then backed on the premises (not homemade, as the waitress is careful to specify, because Charley's "is not a home").Real Trenton crackers, important to those whocare about such things. A salad of venegared iceberg lettuce with grated egg (dull) or a vegetable such as stewed tomatoes that are heavy on the garlic (a favorite seasoning of Charley's, obviously) or fried zucchini cut so think that it is really crusted raw zucchini. You can get anchovy or bearnaise sauce with the grilled fish (neither necessary nor objectionable). And you get service that is (thank goodness) winding down to quiet smothering. a

Some things you should make a point to try: The hot oysters (casino, florentine) and clams (Larry) are plump and moist and spicy and delicious -- at lunch. You may want to try a mixture of the three -- at lunch. At dinner the toppings taste stale and reheated, as apparently does anything they can get away with preparing ahead. Try the linguine with clams; its homemade pasta is thin and delicate, the clams -- though, unfortunately, chopped -- are plentiful and the whole is a buttery, slurpy, briny platter. Mussels steamed in garlic "casino" sauce are fat and fresh. Oysters and clams are available by the quarter -- as well as half-dozen. House wines are pleasant, with a choice of several. (But the specially priced Alsatian wine we tried one night was an $8.50 bottle that tasted like $8.50.) Above all, and against all instincts if necessary, try a dessert called Strawberries, Pepper and Asti. It is truly, peppered strawberries, accompanied by papaya chosen by someone who knows when a papaya is ripe. And it is covered with liquers -- orange and anise -- and cream. Refreshing. Haunting. Sensational. And at $4.50, enough for two if you don't mind sharing the glass of icy, sweet Asti Spumante that comes with it.

There are other things I would happily order if I could have some slight adjustments in them. The raw bar platter ($9 as a lounge lunch entree or dining room dinner appetizer) comes up with a high percentage of successes among its oysters, clams, shrimp and cold poached bluefish (actually, the bluefish is the highlight). Its Dungeness crab, though, would not have been worth the cracking even if we had had an implement, and one shrimp was bitter. Small effort needed to improve. The pan-roasts and provencales (available at lunch, $6.25 to $7.95, with a choice of scallops, crab or oysters) show a kitchen intelligent enough to just lightly cook the seafood, and it is indeed fresh and high quality seafood. But these dishes are swamped in sauce; the panroast, presented as a huge bowl of coral cream with an island of stuffed tomato in the shade of a single parsley tree, prompted a diner to suggest, "I need a straw." And, like the vacation site it resembled, it was full of sand. Not too difficult to carefully strain the steaming broth and to serve the seafoods in an appropriately sized dish with an appropriate amount of sauce.

Some dishes are simply unredeemable. The soups and sauces taste like textbook of formulas gone awry. Charley's chowder calls itself a classic in its own time, and I have heard of people liking it, but its own time must have passed by the time I tasted it: It was a dense and murky mush, strong and tinny and fishy from the pasty bits of overcooked fish. Cheese and corn chowder showed little acquaintance with cheese -- it was mostly floating canned corn. Even worse is the Charley's crab mix that tops the top-priced Lobster Larry and the scrod and apparently is the base for crab balls. Grainy, mushy, with a token show of crab, it is the kind of stuff you want to scrape off a good lobster or fish filet; fried, it is fish lead.

The menu is long, but what the kitchen has conquered are the simple steamed, poached and grilled dishes.

What it has not conquered -- besides elaborations that don't ordinarily take a chain operation anyway -- is timing. Plan for the possibility of a long wait, no matter how simple your order. The wait is not always long, but you never can tell.

You can depend on the service being unfailing pleasant; whatever training can accomplish in lieu of experience, it has accomplished at Charley's. I just wish they didn't work so hard at training their customers: You can order this in the lounge but not in the dining room, that in the dining room but not in the lounge, the other at lunch but not at dinner, the rest at dinner but not at lunch.Some fish can be grilled but not charcoal grilled, other poached but not grilled. Sometimes it seems as if the rule book is for the customers rather than for the staff.

Once you clear away all the schlock, however, to get to the gems, you can find Charley's Crab a very pretty place to enjoy a good piece of fish.