Canadian actress Rachel McAdams attends the German premiere of Sherlock Holmes in Berlin on Jan. 12. She is shooting The Vow in Toronto. (Markus Schreiber/Associated Press)

Australian actor Jessica McNamee will join the cast of The Vow, a romantic drama starring Rachel McAdams now shooting in Toronto.

According to the Hollywood Reporter, she will play the estranged younger sister of Canadian actor McAdams.

McAdams stars with Channing Tatum in the film, based on a real-life story about a New Mexico couple.

Shortly after they were married, Kim and Krickitt Carpenter were involved in a car crash that resulted in a head injury for Krickitt, played by McAdams.

After she awakes from her coma, Krickitt remembers her family, but not her husband. He is not deterred and begins to woo her all over again.

The movie is being directed by Michael Sucsy, the Golden Globe and Emmy Award winning director of Grey Gardens.

McAdams, born in London, Ont., has starred in films such as  The Time Traveller's Wife and Sherlock Holmes. She recently was named one of Hollywood's most bankable actresses by Forbes.com.

McNamee was a star of Australian TV series Packed to the Rafters and also horror film The Loved Ones which screened at the Toronto International Film Festival in 2009.

The Vow is scheduled for release in 2011.