And the box office champion this week is...

LOS ANGELES (Reuters) – "Where the Wild Things Are" topped the North American box office, according to studio estimates on Sunday, a strong start for a film that, like its little boy hero, sailed into somewhat uncharted waters.

The Spike Jonze-directed movie -- which was based on a classic children's book, but marketed largely to adults -- stomped over that hurdle to beat most predictions and take home $32.5 million in ticket sales.

"Tribute must be paid to Spike Jonze, who took a brilliant book and created brilliant film from it," said Dan Fellman, president of theatrical distribution for Warner Bros Pictures, which released the movie.

Fellman said "Wild Things" notched the biggest opening weekend ever for an October release by Warner Bros, and dismissed critics who said it would prove too childish for adults and too dark or scary for kids.

"It looks like they were a little jealous," he said. "We knew exactly what we had. We spent 70 percent of our media buy toward adult audiences."

Finishing second for the weekend was Overture Films' vigilante movie "Law Abiding Citizen," starring Jamie Foxx, which also outperformed expectations to collect $21 million and become that studio's highest-grossing opening.

Third was the low-budget horror film "Paranormal Activity," which relied heavily on word of mouth promotion and scared up $20.2 million in tickets for Paramount Pictures.

"Wild Things" is based on Maurice Sendak's dark but beloved 1963 book, which uses just nine simple sentences to tell the story of a little boy named Max who dons his wolf suit and sails to a wilderness inhabited by fanged and furry monsters.

Jonze, who co-wrote the screenplay, spent five years making the film, which combines live action, puppetry and computer animation, and has said that he did not set out to make a traditional children's film.

It was shot near Melbourne, Australia, and features sand dunes, sea shores and fire-ravaged woods instead of the green forest that magically grows in Max's bedroom in the book.

The director reportedly came under pressure from Warner Bros, who were expecting a more family-friendly treatment, and media reports last year said the studio delayed the release for a year, asking for more work on the production.

Warner Bros Pictures is a unit of Time Warner Inc.

Overture Films is a unit of Liberty Media Corp.

Paramount Pictures is a unit of Viacom Inc.