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What would you do if you could travel in time as a hit man – and then discover that you have to kill the older version of yourself? That's the situation Joseph Gordon-Levitt faces when he's tasked to do just that in the futuristic thriller Looper – with the future version of himself played by none other than Bruce Willis. Watch the video to go behind the scenes…

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In Looper, time travel exists in the future -- but it will be illegal and only available on the black market. When the mob wants to get rid of someone, they send their target 30 years into the past, where a "looper" -- a hired gun, like Joe (Gordon-Levitt) -- is waiting to mop up.

Joe lives the good life with his job as a looper – until one day the mob decides to "close the loop," sending back Joe's future self (Willis) for assassination. Will he kill himself, or team up to get revenge? And what about that time-space continuum?

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Written and directed by Rian Johnson, Looper also stars Emily Blunt, Paul Dano and Jeff Daniels. The movie time travels into theaters September 28.