TORQUAY, County Devon, England — She has been called England's most prolific serial killer, having disposed of some 300 victims during the course of a lengthy life of crime, in such a variety of ways — poisoning, garroting, stabbing, strangling, bludgeoning — that an FBI profiler would have been flummoxed. Lethal she was, and I was here on the English Riviera, hot on her trail.

The undisputed "queen of mystery writers," Dame Agatha Christie, is the best-selling author of all time, outsold only by the Bible and Shakespeare. Each September, this south coast resort town — the most peaceful of places the rest of the year — becomes Britain's murder capital as Christie fans from across the globe hold a festival in her honor.

Today, Torquay (pronounced tor-KEY) hasn't changed much from the September day in 1890 when Christie was born here, during the waning years of Queen Victoria's long reign. Metaphorically speaking, the town resembles an elegant lady whose cashmere and tweeds appear to be of the highest quality but on closer inspection reveal snags and frays.

You can still see Beacon Cove, in Christie's time a ladies-only beach where it was thought suitable for her and her young friends to bathe — even though it was directly below and in full view of the men-only Yacht Club. Facing each other across the harbor are The Imperial Hotel, where Christie danced at balls, and the Grand Hotel, where she spent her honeymoon. The Princess Gardens still provide an oasis of color, and the Princess Pier is a wonderful place for an evening stroll. Sadly, the ornate pavilion where Archie Christie proposed to Agatha Miller in 1913 after a Wagner concert has become a shopping arcade, although the gorgeous Edwardian exterior, ornate ceiling and coat of arms are intact.

These places and six others are stops on the Agatha Christie Mile, a trail that wends around the harbor, and for wannabe Hercule Poirots and Miss Marples, are the scenes of some of her cases (it was on the terrace of the Imperial Hotel, for example, that Miss Marple, on her final case, revealed the culprit in Sleeping Murder).

Nowhere in Devon, however, is as closely associated with Christie as Greenway, the imposing home used by Christie and her family as a holiday retreat from 1938 to 1959. The author described it as "the loveliest place in the world." Since February, when the National Trust opened it to the public, visitors to Greenway have had a chance to judge for themselves.

Arriving by boat on the River Dart and landing in the woodland gardens that slope downhill from the house, it would be hard to argue with Christie's assessment, but the real treasure is the house itself. It is easy to imagine Christie spending summer evenings in the drawing room, reading chapters from her latest novel to the guests at one of her weekend parties. Or maybe presiding over Christmas dinner in the formal dining room, or looking out over the Dart Estuary from her bedroom windows.

In a testament to Christie's enduring popularity, Greenway has experienced a deluge of visitors since its opening. Robyn Brown, National Trust property manager for Greenway, joked, "Do tell your readers to come, but please ask them to wait until next year." (To learn more about Greenway and other National Trust properties, go to the Web site of the Royal Oak Foundation, the U.S. arm of the trust, at www.royal-oak.org.)

From Agatha to Arthur

Just across the River Tamar from Devon is Cornwall, England's most exotic county, where palm trees and orchids flourish (yes, really) and legends of druids, smugglers, and Arthur and Merlin abound. It was Arthur I was in search of, and my destination was Tintagel Castle on Cornwall's rocky north coast, reputed to be the birthplace of England's legendary king.

Legends vary. This was the spot where Queen Igraine of Cornwall, in the absence of her husband, was seduced by King Uther Pendragon, thus conceiving Arthur. Or it was where the infant Arthur was tossed by the waves onto the beach near the cave — accessible at low tide — where Merlin the Magician lived. Either legend works for me.

Tintagel is one of the most dramatic — and other-worldly — settings I've ever seen.

It's situated atop a 300-foot cliff on a peninsula connected to the mainland by a slim thread of land, and it's easy to imagine the saga of Arthur and Merlin playing out here. Reaching the summit requires an ascent of 65 steep steps carved out of stone on the side of the cliff; nevertheless, I was determined to do it.

Once atop the cliff, I was speechless. Above me, curlews and terns circled in a clear blue sky. Below me, waves crashed on the slate cliff rocks. Much of the castle, built in the 13th century on the site where the original was thought to have been, has, over the centuries, fallen into the sea.

I was overcome by a sense of timelessness. Those weren't my fellow tourists combing through the ruins, but the ghosts of Arthur and Merlin, as well as the star-crossed lovers Tristan and Isolde. Tintagel is that kind of place.

Back to the 21st century

Devon and Cornwall are popular destinations for visitors to England, combining natural beauty, history and a host of outdoor activities. For starters, there's Coastal Path National Park, which meanders through both counties and allows walkers to marvel at the scenic wonder of England's southern Atlantic coast.

The Duchy of Cornwall belongs to Prince Charles (he is the prince of Wales and the duke of Cornwall). It has stunning beaches, including Newquay, a mecca for surfers; art colonies (St. Ives is known for sculpture gardens, with works by Henry Moore and Barbara Hepworth, and for its branch of London's Tate modern art museum); and 70 National Trust gardens that are open to the public.

If you have time for only one garden, make it the Lost Gardens of Heligan, deemed by the BBC as "the nation's favorite garden." Heligan's 200 acres include an Italian garden, a New Zealand garden and a sundial garden. There's also a sub-tropical jungle that has to be seen to be believed. With its riot of foliage, including palms, giant rhubarb, banana plantations and towering bamboo, it is easier to imagine you are in the Amazon than in the British Isles.

Devon has one of my favorite destinations in the world: the tiny village of Clovelly, on the north coast. The whitewashed cottages, smothered in scarlet and purple bougainvillea, tumble down a steep slope to a sea that varies from turquoise to sapphire. If the Lost Gardens of Heligan evoke the Amazon, Clovelly conjures the volcanic villages of Greece more than England's gentle, pastoral countryside.

The main street is too steep for cars, so everyone walks, and if you're staying at the New Inn (new being relative — it dates to the 17th century), your luggage will be brought up by a hand-pulled sledge. Until recently, donkeys brought up the heavy loads from the harbor, but now the donkeys' only duty is to take children on summer rides.

In addition to coastal walks, boat trips, arts and crafts galleries, and cozy tea shops, you can peek into tiny chapels and cottages, including the Fisherman's Cottage and Crazy Kate's Cottage, the oldest in Clovelly. You can enjoy a pint at the harborside Red Lion Inn or a peaceful lunch in the honeysuckle-swathed garden of the New Inn. In this idyllic setting, it is easy to understand what novelist Charles Kingsley meant when he wrote about Clovelly:

"Suddenly a hot gleam of sunlight fell upon the white cottages, with their grey steaming roofs and little scraps of garden courtyard, and lit up the wings of the gorgeous butterflies which fluttered from the woodland to the garden."

He wrote those words 150 years ago, but as I sat there, in that same hot gleam of sunlight and watching those iridescent butterflies, it seemed that Clovelly had changed so little that Kingsley might well use those same words if he visited today.