Watch the latest "Avengers: Age of Ultron" trailer

There's a new (third, if you're keeping count) trailer out for "Avengers: Age of Ultron," giving the latest peek at what's in store for Marvel's superhero supergroup.

The video, unveiled Wednesday, sets up the backstory for the villainous Ultron (voiced by James Spader), an artificially-intelligent robot of Tony Stark's creation out to destroy humanity -- and the Avengers too, while he's at it.

It's got some new footage (Thor taunting Ultron and his minions, more of franchise newcomers Quicksilver and Scarlet Witch) and big battle scenes, but watch through to the very end for something even bigger -- the first real glimpse of what looks to be Paul Bettany as Vision.

"Avengers: Age of Ultron" hits theaters on May 1. Check out the trailer below: