Fifth Harmony's next big hit may just be a song that isn't even on their album "Reflection." The group penned a song for the upcoming "Hotel Transylvania 2" soundtrack, and that song is now making the rounds on the Internet ahead of its official release.

According to Direct Lyrics the song, appropriately called "I'm In Love With A Monster," surfaced online on Aug. 3 but is bound to be released soon.

The president of Sony, Lia Vollack, explained, in a statement released in June, why the group were the perfect choice to pen the film's theme song.

"There are few groups out there that can match the incredibly fun feel and animated vision that Genndy Tartakovsky [the movie's director] is bringing to 'Hotel Transylvania 2,' and Fifth Harmony knocked it out of the park," Vollack said. "The song is exactly what we were hoping for."

The Sony Pictures animated film, which stars singer and actress Selena Gomez, comedians Adam Sandler and Kevin James and SNL alum and Brooklyn Nine-Nine star Andy Samberg, is set to premiere in theaters worldwide on Sept. 25.

The group made the announcement, that they would be featured on the soundtrack, back in June on Twitter with a video.

"Can't wait for you guys to see the trailer for 'Hotel Transylvania 2' and hear our song 'Im In Love With A Monster,'" the video was captioned.

The group, currently on tour with special guest Natalie La Rose, is nominated for Choice Music Group, Choice Song: Group, Choice Female Hottie and are scheduled to perform at the 2015 Teen Choice Awards airing on Aug. 16.