Even though "Enigma" has a plot almost as hard to crack as the Nazi coding device that gives this World War II thriller its name, it is such a grand, romantic entertainment that it sweeps the viewer along in its swiftly escalating suspense.

More unpredictable than it first seems, "Enigma" crackles with Michael Apted's vigorous, perceptive direction from a superior script by Tom Stoppard from the 1995 Robert Harris bestseller.

A complex, meticulous period re-creation down to the tiniest detail, this handsome production marks the debut of Jagged Films, founded by Mick Jagger and Victoria Pearman, with "Saturday Night Live's" Lorne Michaels joining in as Jagger's co-producer. "Enigma" could also apply to the beautiful blond Claire Romilly (Saffron Burrows) who is among the many staffers at Bletchley Park, an elegant old country estate 60 miles north of London that the British government turned into a top-secret site for its code-breakers just before the outbreak of World War II. Among her countless pursuers is the brilliant young Cambridge mathematician Tom Jericho (Dougray Scott) recruited to help break the Enigma code.

But the German navy has changed its code--the year is 1943--placing an Allied merchant shipping convoy in the Atlantic with 10,000 passengers and vital supplies at risk from Nazi U-boats.

Jericho, who tells Claire he loves mathematics because "truth and beauty are one," falls head over heels for her. Tom is so besotted with her he suffers a breakdown, only to be returned to Bletchley Park a month later, and learns that Claire has been missing for 14 hours. Gathering his resolve and aided by Claire's smart roommate and co-worker Hester (Kate Winslet), Jericho attempts to break the code while investigating the mystery of Claire's disappearance.

What unfolds is a complex tale of love, betrayal and high adventure as Tom and Hester quickly realize they must stay one step ahead of the Bletchley Park administration and the secret service, represented by the clever and persistent Wigram (Jeremy Northam).

A memorable Ivor Novello in "Gosford Park," Northam is crucial in sparking his scenes with Scott, whose Jericho is listless and dazed upon his departure from a mental institution. Scott, however, expresses Jericho's growing strength persuasively, and Winslet is a delight as one of the movies' most cherished archetypes--the brainy girl who proves to be a beauty under her unflattering glasses.

Seamus McGarvey's burnished camerawork, John Barry's magisterial score, Shirley Russell's costumes and Jenny Shircore's makeup and hair designs are all terrific pluses, but John Beard must be singled out for special praise for his spot-on and evocative production design. When the real Bletchley Park, now a museum, proved impossible to use for exteriors because of all the modern buildings surrounding it, Beard re-created it in the similar Chicheley Hall, also north of London.

While "Enigma" is a clever blend of fact and fiction, it is worth pointing out that the tragic life of Alan Turing, the actual mathematical genius of Bletchley Hall, was dramatized in the play "Breaking the Code," in which Derek Jacobi won great acclaim as the tormented Turing.

MPAA rating: R, for a sex scene and for language. Times guidelines: complex adult situations.

'Enigma'

Dougray Scott...Tom Jericho

Kate Winslet...Hester Wallace

Jeremy Northam...Wigram

Saffron Burrows...Claire Romilly

A Manhattan Pictures International presentation of a Jagged Films/Broadway Video production. Director Michael Apted. Producers Lorne Michaels and Mick Jagger. Executive producer Victoria Pearman. Executive producers Guy East and Nigel Sinclair; Hanno Huth and Michael White. Screenplay Tom Stoppard; based on the novel by Robert Harris. Cinematography Seamus McGarvey. Editor Rich Shaine. Music John Barry. Costumes Shirley Russell. Production designer John Beard. Art directors Rod McLean, Stuart Rose. Set decorator Eliza Solesbury. Running time: 1 hour, 57 minutes.

At selected theaters.