Robert Downey Jr. brings the legendary detective to life as he has never been portrayed before. Jude Law stars as Holmes' trusted colleague, Watson, a doctor and war veteran who is a formidable ally for Sherlock Holmes. Rachel McAdams stars as Irene Adler, the only woman ever to have bested Holmes and who has maintained a tempestuous relationship with the detective. Mark Strong stars as their mysterious new adversary, Blackwood. Kelly Reilly will play Watson's love interest, Mary.