Paramount's spy thriller The Sum of All Fears exceeded expectations and shot to the top of the charts over the weekend, overthrowing Star Wars: Episode II, with an estimated $31.2m gross.

Clones was shunted to second spot on $20.7m, bringing its cumulative total to $232m after 18 days. Spider-Man slipped to third with $14.5m in its fifth weekend on release and has now amassed $354m. This means Sam Raimi's Marvel Comics adaptation needs only another $3m to overtake Jurassic Park and become the fifth-highest grossing film of all time in the United States. Spider-Man's rollercoaster success also means that for the first time a Star Wars movie will not be the year's highest earner.

The Sum of All Fears is the fourth instalment of thriller writer Tom Clancy's Jack Ryan series and the third incarnation of the lead character in the form of Ben Affleck. Alec Baldwin first assumed the role in The Hunt For Red October in 1990 and was followed in 1992 by Harrison Ford in Patriot Games and Clear And Present Danger two years later.

The latest episode sees Affleck grappling with renegade Russian terrorists and is set against a backdrop of deteriorating relations between the United States and Russia. Morgan Freeman and James Cromwell co-star. Studio executives were concerned the movie's storyline would be inappropriate in the wake of September 11, especially in view of one scene depicting a nuclear blast over Baltimore. However the robust opening results and enthusiastic exits-polls among a sizeable over-25 demographic confirmed that audiences want a gritty alternative to lightsabres and spiderwebs.

Overall, the top 12 movies grossed an estimated $116m, down 5% on the same period last year and a 24% drop from the equivalent three-day portion of last week's record-breaking Memorial Day Weekend.

However much of the slack can be attributed to the NBA basketball play-offs, which will have kept a large portion of the market glued to the small screen.

Universal's comedy Undercover Brother fared well in its first weekend and opened in fourth place on $12.4m. The picture garnered decent write-ups and has an Austin Powers feel to it. It stars Eddie Griffen as a funky 70s-style dude who has to save the world from a shadowy foe called The Man.

Elsewhere, DreamWorks's animated equine romp, Spirit: Stallion Of The Cimarron, fell one place to fifth on $10.7m and has now taken $38.2m. Insomnia, the mature thriller from Warner Brothers that stars Al Pacino and Robin Williams in a guilt-laden game of cat-and-mouse, fell three places to sixth on $9.8 and has now taken an impressive $41.4m after only ten days on release.

Next week's releases see Anthony Hopkins and Chris Rock dancing to an old tune as unlikely partners who must save the world in Buena Vista's spy comedy caper Bad Company and a stellar cast featuring Ellen Burstyn, Ashley Judd and Sandra Bullock in Divine Secrets Of The Ya-Ya Sisterhood for Warner Brothers.

Film (Distributor)/Int'l dist/Estimated weekend gross/Estimated total to date
1 (-) The Sum of All Fears $31.2m --
2 (1) Star Wars: Episode II - Attack Of The Clones (Fox) Fox International $20.7m $232m
3 (2) Spider-Man (Columbia) Columbia TriStar $14.5m $354m
4 (-) Undercover Brother (Universal) UIP $12.1m --
5 (4) Spirit: Stallion Of The Cimarron (DreamWorks) $10.7m $38.2m
6 (3) Insomnia (Warner Brothers) Warner Brothers $9.8m $41.4m
7 (5) Enough (Columbia) Columbia TriStar $6.8m $27.1m
8 (6) About A Boy (Universal) $4.1m $27.8m
9 (7) Unfaithful (20th Century Fox) Fox International $3m $45.7m
10 (8) The New Guy (Columbia) Columbia TriStar $1.5m $26.9m