The implausible escape of a brilliant murderess brings U.S. Marshal Teddy Daniels (Leonardo DiCaprio) and his new partner (Mark Ruffalo) to Ashecliffe Hospital, a fortress-like insane asylum located on a remote, windswept island. The woman appears to have vanished from a locked room, and there are hints of terrible deeds committed within the hospital walls. As the investigation deepens, Teddy realises he will have to confront his own dark fears if he hopes to make it off the island alive. Such was the premise of the Martin Scorsese horror-thriller 2010 masterpiece. And though you might have seen and enjoyed the movie multiple times, here are some interesting facts about it that you might not know about Shutter Island.

• Mark Ruffalo won the role of Chuck Aule after sending Martin Scorsese a fan letter saying how much he wanted to work with him.

• Before deciding on Ruffalo, Leonardo DiCaprio and Martin Scorsese also considered Robert Downey, Jr. and Josh Brolin.

• The movie's 40.2 million dollar opening weekend take in the U.S. marked a career best for Scorsese. It went on to gross over 293 million dollars worldwide, making it the highest grossing film of his career. This was later surpassed by The Wolf of Wall Street (2013).

• This is the only film of the partnership between Martin and Leonardo that failed to receive any Oscar nominations. Gangs of New York (2002), The Aviator (2004), The Departed (2006), and The Wolf of Wall Street (2013) all received Oscar nominations, including for Best Picture.

• To give his cast members an idea of how his film would be stylistically, Scorsese screened Out of the Past (1947) and Vertigo (1958) for his cast and crew.

• The working title for the film was "Ashecliff", the name of the insane asylum.

• The ball-point pen Teddy uses in the film is a Parker Jotter, it was released in 1954 (the year the film takes place).

• The film cast includes two Oscar winners: Sir Ben Kingsley and Leonardo DiCaprio; and five Oscar nominees: Max von Sydow, Mark Ruffalo, Michelle Williams, Jackie Earle Haley, and Patricia Clarkson.