The Forge, 14 Garrick Street, London WC2

The Forge is the new eating-house from Robert Seigler who gave the capital Le Café du Jardin and Le Deuxieme, both with a WC2 address. This, his third Covent Garden restaurant (is it time to have a word with the Monopolies Commission?), is on the site of what used to be Inigo Jones, a restaurant with a reputation for being scarily over-priced. It's a peculiar, faux-Gothic building, matched by the deeply peculiar décor, menu and cooking of The Forge itself.

My guest, Amanda, and I sat in a kind of corridor outside the main dining area, trying to work out why the new owners had laid one wall to exposed bricks (nice homely touch) but installed silver panelling in the ceiling (nasty Doctor Who touch) and why the paintwork, though aspiring to Kelly Hoppen, looked like it came from B&Q.

The menu is huge in every sense: larger than a page of The Independent, crammed with dishes apparently chucked in at random, and drawn from all corners of the world. The 20 (20!) starters comprise a dozen ancient and boring standards you'd find on the dinner menu at the Garrick Club across the road (French onion soup, Welsh rarebit, omelette, smoked salmon, devilled lamb's kidneys, Essex oysters). The others offer a whistlestop tour of world cuisine, throwing French, Italian, Japanese and Lebanese bits in together: "Tempura of smoked haddock with parsnip tabouleh [sic]"? "Serrano ham, Charentaise [sic] melon and caperberry salad"?

If you're not yet baffled, the next section of the menu offers seven dishes available in small or large portions, mostly dishes you'd find in a third-rate trattoria in deepest Surrey (linguine vongole, tomato risotto, rigatoni with spinach, Parmesan and ricotta). But who would come to Covent Garden to eat a tomato risotto costing £14? A glanceat the 20 (another 20!!) main dishes makes your head spin with the crackpot internationalism of it all: chicken Kiev (seriously), monkfish with chorizo paella, pork with Japanese udon noodles and Chinese barbecue sauce. Among the 16 side orders (16!!) you could order a helping of spaghetti Napolitana.

"It's like having a worldwide Rambler ticket," said Amanda. Perhaps it's precious (or old-fashioned) of me to complain about restaurateurs who pestle together the cuisine of several countries. If it's done well it can be fine – monkfish and chorizo, say, without the paella – but too often it's a car crash of styles and flavours. Not so much fusion, as utter confusion.

Anyway, the starters came. Amanda had the seared scallops, mushrooms, pea and mint foam, and inspected it suspiciously. Three roundels of scallop sat on a mushroom bed surrounded by verdant froth. "This isn't scallops plural," she pointed out. "It's three slices of one scallop. Somebody else has probably got the rest of it." It was true. The mushroom quite overwhelmed the thin slivers of shellfish. We watched as the "pea and mint foam" simply disappeared from her plate, like the spume of an ebb tide.

My "sauté of tiger prawns and squid with coriander, garlic, ginger and chilli" arrived with the prawns in their tail-shells and a garnish of grated carrot. I'd love to tell you how it tasted, but the whole dish was, for some reason, awash with teriyaki sauce, as if someone had upended a bottle of the stuff over my plate. "Have you upset the chef?" asked Amanda. "I can smell that from over here." It's bad enough removing prawn shells when they're slick with dressing. But when they're drowning in sauce ...

A little alarmed, we hit the main courses. The roasted guinea fowl with baby leeks and truffle jus came in two large lumps and looked fine. Sadly, it tasted of anything but guinea fowl. "If this were a blind tasting," said my guest, "I'd have said it was chicken. There's no game quality about it at all."

We began to feel a little guiltily negative. But then my veal Holstein with a fried quail's egg was plonked down before me. Nothing more dispiriting, more redolent of a 1950s café supper can be imagined than the sad lump of breadcrumbed depression that lay on my plate – and on it, with all the presence of a dead sparrow on an old mattress sat the teensy egg, fried about half an hour earlier, utterly pointless and sad. I felt sorry for it. The veal tasted of chicken nuggets. A side order of dauphinois potatoes was a portion-control block of school-refectory spud, creamless and heated from the bottom. A dish of French beans came unadorned by butter, oil, or any seasoning.

The waiter was charming and attentive, and kept asking, "Did you enjoy that?" as each plate was cleared. He nodded enthusiastically, as if willing us to enjoy this parade of careless ineptitude. We didn't complain for fear of spoiling his evening. Gingerly, we ordered pudding from the 12-dish list. Amanda had the baked Williams pear with Roquefort cheese and walnut crumble. The pear and cheese were fine, but Roquefort simply does not go with sugary things like crumble. As so often, this restaurant slung in one ingredient too many. My tarte tatin was passable, but the apple lumps had a squashed, defeated air when you wanted them fat, chunky and triumphant (and preferably made on the premises).

I've seldom been so depressed by an eating experience. The only good bit was a bottle of The Custodian, one of the wonderful D'Arenburg wines from Oz – £8.99 in Oddbins, £28 here. Otherwise, I left The Forge wondering how long they can dish up such hopeless chain-eaterie fare at such fancy prices and get away with it.

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The Forge, 14 Garrick Street, London WC2 (020-7379 1432). About £112 for two including wine