The second official trailer for The Avengers has assembled, and if the first one whet your appetite for the Marvel summer tentpole, this one should have you champing at the bit. The action begins with Loki waging war against the U.S. military, and Samuel L. Jackson's Nick Fury calling on a ragtag band of superheroes to save the planet. We get closer looks at Jeremy Renner's Hawkeye and Scarlett Johansson's Black Widow, and a thrilling sequence in which the Hulk grabs a plummeting Iron Man in midair, saving him from imminent doom. The trailer should help assuage nervous fans about whether writer-director Joss Whedon is able to pull it off at the same time it raises anticipation levels through the roof. The Avengers opens in theaters everywhere on May 4th, 2012. Click through to view the trailer.