Okay. Part of me here thinks that, after his girlfriend was killed, Adam Levine's character lost his sanity and developed a taste for blood. When he sees the object of his latest desire —played by real-life wife Behati Prinsloo — on the job, he develops an unhealthy obsession that he can't wait to enact in reality.
Another part of me thinks that Adam's studied a lot of Criminal Minds episodes and may wish to be a serial killer in his next big film role; This could be considered his audition.
I'm going with scenario three: Maroon 5 reunite with Samuel Bayer to take the primal nature of the song to an extreme - and make sure there are no CGI gerbils driving Kia Souls.
Whatever the case, Adam's having a grand old time in that meat locker. It's worth a few clicks. And Bayer probably loves the opening credits to Se7en as much as you do.