A viral website campaign has kicked off for director Guy Ritchie's mystery action adventure Sherlock Holmes, starring Robert Downey Jr., Jude Law, Rachel McAdams, Mark Strong, Kelly Reilly and Eddie Marsan.

Access the site here and type in "IRENE" (for Rachel McAdams' character Irene Adler) in the boxes to watch a video of a hooded man, followed by page where you can sign up your e-mail for further updates.

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In the Warner Bros. picture, which opens in theaters on Christmas Day, Holmes and his stalwart partner Watson take on their latest challenge. Revealing fighting skills as lethal as his legendary intellect, Holmes will battle as never before to bring down a new nemesis and unravel a deadly plot that could destroy the country.