Adrian Grenier, the environmentalist and filmmaker best known for his starring role on HBO "Entourage," has signed up to produce a documentary about a mysterious and unidentified species of whale. 

Titled "52," the new film will follow a team of scientists as they attempt to track down a whale deemed "the loneliest whale in the world" because of its unique call frequency. While other species such as the blue whale and the fin whale communicate at between 15-20 hertz, this unique whale calls at 52 hertz. Discovered in 1989, the whale's movements have been tracked by scientists at Woods Hole Oceanographic Institution, with migrations as far north as the Aleutian and Kodiak Islands and as far south as the California coast.

"We don't know whether he sounds that way because he's a hybrid of a blue whale and a fin whale or if he's a blue whale with a physical deformity that causes him to sing at 52 hertz," marine biologist Mary Ann Daher told the UK Express last year.

Directing "52" is Joshua Zeman, who will undertake a seven-week expedition in the Pacific this fall to start filming and, hopefully, locating the mysterious whale. 

"“I’m so humbled by the scope of this adventure,” Zeman told Variety. “There is still so much mystery in our oceans and the plight of this lonely whale speaks to something very human in all of us; the need to connect and be heard.”

"52: The Search for the Loneliest Whale in the World" is expected to open sometime in 2015. 

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Michael d'Estries ( @michaeldestries ) covers science, technology, art, and the beautiful, unusual corners of our incredible world.

Adrian Grenier producing documentary about 'the world's loneliest whale'
Mysterious whale produces a sonic frequency of 52 hertz that is unique in the world's oceans.