WORLDWIDE blockbuster The Da Vinci Code moves from book format to the movies on May 19 and key parts of the action are based in Paris, where fact and fantasy combine in a glorious cocktail of adventure and intrigue.

WORLDWIDE blockbuster The Da Vinci Code moves from book format to the movies on May 19 and key parts of the action are based in Paris, where fact and fantasy combine in a glorious cocktail of adventure and intrigue. NIGEL PICKOVER went on a weekend dash to the French capital to trail-blaze a walk that is set to become very popular this year.

IRIS Spencer, fast-paced and fast-talking university graduate from Indiana, USA, could be a character straight out of Dan Brown's worldwide bestseller The Da Vinci Code.

Articulate and intelligent, Iris, 35, is unlike the book and film's star Professor Robert Langdon, in that she is a very real American in Paris … and about to enter one of the busiest phases of her fascinating life.

For Da Vinci Code fever is about to strike and Iris will be at centre stage in Paris as the film, starring Tom Hanks as Langdon, sends droves following in the footsteps of the book and screen characters.

Iris, who works for Paris Walks, guides tourists around the sights and sounds of some incredible locations and now, courtesy of multi-millionaire author Mr Brown, has a new chapter in her own book.

After studying the epic Da Vinci tale - an electrifying search for the Holy Grail - in forensic detail, she has overlaid her knowledge of the “fiction” on the factual locations where the action has been set.

Her walking tour, over two fast-moving hours, enhances enjoyment of both the book and the sight-seeing of some parts of Paris that visitors would not normally get to.

To put my visit to Paris - and Iris's work - in context, those who haven't yet read The Da Vinci Code, need to know a few details. But, if you are just about to bury yourself into the 600 or so spellbinding pages, don't worry … I won't give away any key secrets:

· US professor Robert Langdon (Tom Hanks in the movie) is awoken in the middle of the night by French detectives who want him to help them solve a baffling, horrific, killing at the gigantic Louvre - the world-class museum next to the River Seine.

· Langdon, an expert in ancient symbols, tries to unravel a code left at the scene and is joined by a police department cryptologist, Sophie Neveu. Clues involve Da Vinci paintings on show in the museum.

· The pair discover that the victim, Louvre curator Jacques Sauniere, has given his life to protect and ancient code and that it is linked directly to the location of the Holy Grail.

· A deadly game of cat and mouse is then played out in Paris, London and Scotland as the search for the Grail, or San Greal (royal blood) moves with lightning speed.

My meeting with Iris began in the clandestine style of the book … at the little-known Mabillon metro station, an unremarkable rendezvous point close to the Seine.

At the appointed 10am time, our small group had no sight of her. With a clear view all around, I kept my eyes peeled. Still nothing. And then, as if by magic, she was there at my side, quite how I do not know.

Our first destination was St Sulpice Church, founded in 1646, a location which is featured in the opening chapters of the book. Here, in the land of fiction, the albino monk, Silas, a real baddie if ever there was one, thinks he can find definitive clue to lead him to the Holy Grail.

Here, in reality, is a Rose Line - a narrow brass strip, which marks the original zero-longitude line, which passed through Paris, before Greenwich in London snatched the “meridian” all to itself.

Inside the vaulted calm of St Sulpice, Iris helps you to trace Silas' path across the nave to an obelisk next to the statue of St Peter … and here I must leave this part of the plot.

Plunging onward through the back streets of Paris, the next stop was at the Romanesque church of Saint Germain-des-Pres, consecrated in 1163, which has its own deep roots to the world of Knights Templar and the Grail legend.

Here Iris told more of the Paris links in the Da Vinci story, including details of the recent filming for the May release. Then she spotted a street marker for the Rose Line - apparently the first “trail” followers have started stealing these as souvenirs.

Next it was on the banks of the Seine, where the Louvre forms an impressive backdrop. The first thing that strikes you is the size of the place - it's a three mile hike if you walk around the outside walls.

The Louvre, Iris reminded me, features the murder of Sauniere, the escape of Langdon and the decoy tactic when a tracker, hidden in on our hero's pocket by a detective, is pressed into a bar of soap and thrown on to a lorry which drives off into the Paris night.

The tour was coming to an end as we entered the inner courtyard of the museum with its controversial glass Pyramid entrance in the distance. There was just time for Iris to lead the way into the underground Carrousel entrance to the Louvre, with its own inverted pyramid as a centre point.

Here history and modernity, fact and fantasy, and book and film, collided.

It was a great way to spend the first morning of a short-break in Paris, and it made me want to race back to the hotel to start my second reading of Dan Brown's work. Scholars may have panned the book but there's no doubt about its phenomenal success and the sightseeing storm that has been created.

One example of this comes at the ornate 15th century Rosslyn Chapel, in Scotland, where a trickle of vistors a few years ago has now swelled dramatically. More than 100,000 visitors are expected this year as devotees from around the world follow the British end of the Da Vinci Code trail, which leads to Scotland and Rosslyn.

Mr Brown's book did huge favours for his bank balance … but helped quite a lot of other causes too.

The walking tour was a thrilling start to a great weekend and added further sparkle to my enjoyment of a memorable book. It was well worth the trip!

Taking the Da Vinci trail provided a memorable short break in more ways than one - it allowed me to re-discover the joys of Paris in the spring time.

Paris has a well-developed and efficient underground system - the Metro - but my wife and I decided we would walk everywhere on foot ... and had a great time discovering landmarks we hadn't seen since our first visit there 25

years ago.

Our base was the Hotel Westminster, a small but sophisticated hotel close to the Paris Opera house, and the perfect base for exploring.

In one direction lay a five-minute walk to the Place de Vendome, Rue de Rivoli and the Tuileries gardens and Louvre beyond.

In the other, beyond the opera house and it phantom legend, was a 45-minute walk to Montmatre and the incredible Sacre Coeur edifice, with super views over Paris.

We walked everywhere and thoroughly enjoyed ourselves, taking in a coffee and cake at a street bar here and a glass of wine at another a mile along the street.

For lunch on the Saturday of our visit we visited a restauanrant near the opera house and shared a large plate of seafood,

delivered with style and grace for £35 and, late into the evening we went out to another eaterie close to our hotel.

We had a set meal, with wine and coffee, for a total of £50, and strolled back to our hotel in the early hours feeling we had enjoyed great value for money.

The Westminster provided great breakfasts - enough good food to power those long walks. On the Sunday, before our return, we walked to Place de La Concorde and on, via the Champs Elysees, to the incredible Arc de Triomphe.

We enjoyed Paris so much we plan a return, with my wife planning a shopping spree in all those premises we had to miss out on this time around. On second thoughts …

Where: Paris, France

How to get there:

Take the train from Ipswich to the French Capital. We took One Railways to Liverpool Street, the Tube to Waterloo, where we picked up a Eurostar express. The two-hour-20-minutes journey from London to Paris was non-stop.

What to do:

Dan Brown Da Vinci Code walking tours are available through 'Paris Walks'. For further info and bookings call: (33) 01 48 09 21 40 or see www.paris-walks.com . Two-hour guided walks cost from £8 per person.

Cost: Thomson's Cities and Short Breaks programme offers city breaks to Paris all year round.

Two nights at the four-star Hotel Westminster, near Opera, costs from £369 per person in May. Packages include return Eurostar (standard class), breakfast, accommodation and a Paris pop up map.

Two nights at the two-star hotel Leonardo De Vinci,near Republique, costs from £147 per person in May.

Contact: Thomson Cities and Short Breaks on 0870 606 1477 or see www.thomsoncities.co.uk

Hospitality: The author and his wife were guests of Thomson.