Guillermo del Toro began working on the script for The Shape of Water while making Pacific Rim, and as works like Crimson Peak and The Strain consumed his attention, the director’s fantasy project lingered in the shadows of Hollywood—until now. While it’s all still very mysterious, Fox Searchlight announced the start of production today, confirming the main cast and a few small plot details.

All we know officially about The Shape of Water is this brief, cryptic logline:

THE SHAPE OF WATER is an other-worldly story, set against the backdrop of Cold War era America circa 1963. A mysterious and magical journey from Guillermo del Toro.

Even that, though, brings to mind Pan’s Labyrinth, arguably the filmmaker’s most famous and acclaimed work that featured a fantastical story of fairies and magic contrasted by the historical setting. Earlier this year, a rumored plot synopsis circled the Web, claiming The Shape of Water centered around a mute janitor named Elisa working in a lab that houses an amphibious man. Swayed by her affection, she then reportedly helps the creature escape the facility into the dangerous world beyond his confinement.

Sally Hawkins, Michael Shannon, and Richard Jenkins joined the cast around May of this year, with Shannon said to be playing a villainous role. The press release for the start of production reveals new additions Doug Jones (Crimson Peak), Michael Stuhlbarg (Steve Jobs), and Octavia Spencer.

Del Toro will direct and co-wrote the screenplay with Vanessa Taylor, who worked on the Divergent movie script and wrote episodes of Game of Thrones. Also enticing is the involvement of some creatives, including Crimson Peak and John Wick 2 cinematographer Dan Laustsen as director of photography and visual effects supervisor Dennis Berardi, who worked on Pacific Rim and Fight Club.

No release date has been announced for The Shape of Water, but it could hit theaters as early as sometime next year.

UPDATE: Check out the first title treatment via del Toro’s twitter.