You might be wondering what a contemporary hip-hop song is doing in a trailer for 'Gangster Squad,' a dramatic action film about gangsters in the 40s. Or you're just rolling with it because the trailer is awesome and that song kicks it pretty hard... What is that song, anyway?

The song is "Oh My God" by Jay-Z from his 2006 album 'Kingdom Come.' The track was also previously used in a season six promo for the television series '24,' but it works pretty well here too because Jay-Z has a certain touch that one might describe as, well, baller.

The trailer for 'Gangster Squad' premiered online today, featuring all the guns, gambling, pretty dames, and Ryan Gosling we could ask for from a 40s gangster pic. Okay, maybe not Gosling, but why would you question that?

From director Ruben Fleischer, 'Gangster Squad' mashes up old school sensibilities with new, featuring modern directing flourishes over a classic tale with noir touches. Gosling and Josh Brolin star as cops out to take down mafia types in 40s and 50s era Los Angeles. Sean Penn stars as gangster Mickey Cohen and Emma Stone reunites with her 'Crazy Stupid Love' co-star Gosling as, once again, his love interest.

Check out the full Jay-Z track below, as well as the shoot 'em up trailer for 'Gangster Squad' which hits theaters this year.