This trailer gives us a much better feel for the film. It goes beyond the basic premise and shows the present (Jospeh Gordon-Levitt) and future (Bruce Willis) Joe talking in a dinner and working out what is happening.
In Looper, time travel will be invented — but it will be illegal and only available on the black market. When the mob wants to get rid of someone, they will send their target 30 years into the past, where a “looper” — a hired gun, like Joe (Gordon-Levitt) — is waiting to mop up. Joe is getting rich and life is good… until the day the mob decides to “close the loop,” sending back Joe’s future self (Willis) for assassination.

LOOPER comes to a theater near you on Sept 28th.