Shutter Island’s unbelievably ambiguous ending is actually very different in the book

Picture the scene: it's 2010, and you've just spent an afternoon at the cinema with your mates watching Leonardo DiCaprio's Shutter Island.

The credits start to roll, and you all turn to look at each other, baffled: "What? So he was a patient the whole time? So did the experiment work?"

The psychological thriller was adapted from author Dennis Lehane’s bestselling book, and followed DiCaprio as he took on the role of US Marshall Teddy Daniels, who was sent to an institution for those deemed criminally insane to investigate a missing patient.

Though a few flashbacks drop hints about Teddy's history, it's not until the end of the film that the US Marshall learns he's actually a patient himself; one who was sent there after murdering his wife and children.

Teddy has come up with the story of the missing patient to help him deal with the trauma, and the staff decide to go along with it to see if it will help him accept reality. When that doesn't work, they decide to give him a lobotomy.

The question is, did Teddy actually know the truth?

The movie implies he does know that he killed his family but simply doesn't want to admit to it, as he asks his supposed 'partner', played by Mark Ruffalo, whether it's better to 'live as a monster, or die as a good man'.

Paramount Pictures

The baffling ending is one that has stuck with viewers for more than a decade, with one fan commenting: "The ending to Shutter Island was one of the best I’ve seen, I loved that scene man. So many convos conveyed [through] just eye contact between the characters."

Another wrote: "the ending in Shutter Island has to be one of the best twists of the 21st century film industry."

However, if you've read the book, then you'll know the ending to Shutter Island wasn't always so ambiguous.

Unlike the movie adaptation, the book doesn't include Teddy's final conversation with his partner, and clearly shows him accepting the fact he murdered his wife and children.

He doesn't revert back to his imaginary story, and instead voluntarily submits to a lobotomy.

That's definitely not to say the ending is any less captivating, though, as fans of the book have praised the way Lehane brought it to a close.

"Just finished reading the book "Shutter Island". Wow, what a mindblower of an ending!," one impressed person wrote.

Knowing how they differ, which ending would you prefer to believe?