Rachel McAdams has just wrapped shooting Sherlock Holmes for Guy Ritchie, with Robert Downey Jr. as Holmes and Jude Law as Watson. She plays Irene Adler, a character from the Sir Arthur Conan Doyle story "A Scandal in Bohemia."

At the press junket for the journalism thriller State of Play on Friday in Beverly Hills, Calif., McAdams told a group of reporters about her experience on Holmes, including its tone and its bromance. The following Q&A features edited excerpts of that interview.

What can you tell us about Sherlock Holmes?

McAdams: It's pretty big. I didn't realize how big it was until I stepped on the sets, and they were just massive. It's in true Guy Ritchie fashion, too. It's lots of fighting and explosions, but, I think, from what I've seen, obviously Robert Downey Jr. is an amazing actor, and so is Jude Law. They make a wonderful duo. I think some people are probably skeptical. Everybody has their preconceived notions about Watson in particular. Everyone's like, "Watson's supposed to be like this." Anyway, I just think Jude is a perfect Watson, oddly enough, and they're really perfect together. That's kind of the love story, actually. I play supposedly Sherlock's love interest, but it's really Watson.

You were surprised—did you expect a costume parlor drama?

McAdams: Well, I didn't know what to expect. I didn't know, and I didn't know if it would be kind of a satire of Sherlock Holmes in some ways, or they'd really want to boost up the comedy. It's a really nice balance of the two. It's quite serious and quite heart-pumping, and, at the same time, there's humor in these light moments, too. I've seen just a little sizzle reel of it, and it looks beautiful.

Do you get some cool costumes?

McAdams: I get the best of both worlds, because Irene goes undercover and she wears men's clothes, but she also wears these beautiful, really outlandish bustles. She wears hot pink all the time. She's not afraid to stand out in a crowd.

Does that help get you into character?

McAdams: Oh, yeah, it's so helpful.

What is the year like for you, with this and Time Traveler's Wife coming out later?

McAdams: Oh, who knows? It's going to be busy, that's for sure. It's already busy. I don't know. It's exciting. I'm really glad that everything's coming out. I'm glad it's not all coming out on top of each other. I'm just excited. The films are all very different, which is great. We'll see what happens.