Massimo Restaurant and Oyster Bar, The Corinthia Hotel, 10 Northumberland Ave, London WC2

Elegant: Massimo is a sepia-tinted tableau of steam-age glamour

It happens sometimes in a foreign city. You leave the tawdry, neon-lit sprawl of the main drag and wander down an unpromising side street, only to stumble across The Perfect Restaurant – golden and gorgeous and oozing relaxation and low-key glamour. Emerging hours later, as though from a dream, you forget to note the name of the restaurant or the street, and when you return, you never manage to find it again.

Weirdly, given that I'm meant to know all about new restaurants, a version of this happened to me in my home city the other week. A friend invited me for dinner at a new hotel I'd never heard of, The Corinthia, which opened earlier this year on Northumberland Avenue, a street off Trafalgar Square that appears on the Monopoly board but otherwise doesn't feature very largely in London life.

We had a perfectly OK meal, in an expensively bland, modern British restaurant. And then we set off to explore the rest of the hotel. Creeping down marbled corridors, past shadowy cocktail bars, we arrived at a discreet, unmarked door. 'Ah, this must be Massimo – let's look!' said my friend, and I agreed, though I had no idea what Massimo might be.

We pushed open the door, and by God, there it was – the Dream Restaurant. A vast, elegant, Deco-ish brasserie, a sepia-tinted tableau of steam-age glamour, with its own lost tribe of interesting, arty-looking customers. Acres of conker-coloured leather banquettes stretched into the distance. Huge, hemispherical light fittings set the mosaic marble floor twinkling, and a parade of candy-striped Corinthian columns lent the room a fantastical, cartoonish dimension, like the Wolseley reimagined by Dr Seuss.

That such a stunning restaurant could slip on to the scene without my even noticing says something about the frenetic pace of restaurant openings in London. One reason may be that the Corinthia's Maltese owners haven't gone down the celebrity chef route with Massimo – though its chef-patron, Massimo Riccioli, is well established in Rome. The rest, as they say, is geography – Massimo is located in a monolithic no man's land between Whitehall and Covent Garden, an area with little to detain the passing pleasure-seeker.

I returned to Massimo for a proper, dressed-up dinner a few nights later with a real sense of anticipation, not to say jeopardy – having discovered the perfect restaurant, would the food be any good? Italian seafood is Massimo's speciality – and heretical though it may be to say it, I can never get too excited about eating fish. But once again, I was struck by the beauty of the room (the creation of uber-designer David Collins, I now know) and the mood-enhancing glow of the amber-hued lighting – less than helpful, it turned out, when it came to reading the tiny grey print of the menu.

A single breadcrumbed mussel and a shot-glass of foamed pumpkin soup arrived almost as soon as we sat down, followed, at a slightly erratic pace, by some pretty decent modern Italian dishes. Spaghetti, with a blowsy, oily sauce of porcini and diced calamari, delivered a big slap of Mediterranean flavours, as did grilled octopus, smoky and tender, served with a subtle aioli. Both mains featured shimmeringly fresh fish and pitch-perfect confidence with saucing; John Dory came anchored by a bisque-ish pumpkin and crab sauce, while sea bass was partnered with the crispest of battered prawns and a lemon sauce to underscore the Asian influence.

The precise details are a little hazy, to be honest, thanks to the alacrity with which our wine glasses were refilled, and the longish waits between courses, which meant we'd polished off our entire bottle of Friulano before our mains arrived. Our lovely waitress had a clever trick of warning that certain dishes would take "around 14 to 15 minutes to prepare", the time so oddly specific that she won our trust, even though the actual wait turned out to last a lot longer.

The general impression, though, was that the food, while not quite a match for the room, was pretty darned good. Less so the puddings, which seemed relatively perfunctory: a salted, spiced crème brûlée and a not particularly interesting cherry soufflé with dark chocolate ice-cream.

Never mind. The magical atmosphere, golden lighting and charm of the staff lulled us into an almost trance-like state of well-being and we were congratulating ourselves on finding a new restaurant we'd definitely want to return to – epic but informal, special occasion without being stuffy. And then we got the bill. Ah. Bit of a shocker. The food alone came to £60 a head and with the addition of drinks and service, we paid a sobering £130 a head in total.

So it turns out that in keeping with Massimo's Monopoly board location you need Monopoly money to eat there. We stepped out into the night, in classic foreign-city fashion, knowing we'd probably never return. Not so much the restaurant of your dreams, after all, as the in-your-dreams restaurant.

Massimo Restaurant and Oyster Bar, The Corinthia Hotel, 10 Northumberland Ave, London WC2 (020-7998 0555)

Food ***
Ambience *****
Service ***

Three courses à la carte £60 a head before wine and service

Tipping policy: "Service charge is 12.5 per cent discretionary, of which 100 per cent goes to the staff; all tips go to the staff"

Side Orders: Seafood specials

Ondine

Luxury Edinburgh eatery – try the roast sea bass with creamed spinach and shellfish butter sauce (£21.95).

2 George IV Bridge, E'burgh (0131 226 1888)

The Seahorse

Cooked over a charcoal fire, the seafood here has received rave reviews. Don't miss the roasted monkfish with herbs and olive oil (£24.50).

5 South Embankment, Dartmouth (01803 835147)

Wright Brothers Soho

This sleek fish restaurant and oyster bar brings the freshest stock straight from Cornish fishing boats to the West End.

13 Kingly Street, London W1 (020-7434 3611)