Gints Zilbalodis wordless animated movie Flow follows a little black kitty whos navigating a flood in a post-apocalyptic, seemingly post-human world. The cat finds a boat, encounters a host of different animals, and slowly sails with them through the rising waters. Its a tense adventure with absolutely stunning animal animation: The creature characters experience a full range of emotions as they navigate this strange abandoned world without a lick of dialogue.There are no people on the screen in Flow, but there are hints that people once lived in this world houses, boats, and other structures. Perhaps most heartbreaking, our kitty hero starts off his adventure in an abandoned house that has a soft bed and cat sketches and statues that might be of the black cat itself, suggestions that perhaps the cat once had a human companion.Ahead of the movies Dec. 6 wide release, Zilbalodis told Polygon that while he didnt map out exactly where the humans went in the world of Flow, he did have a sense of what happened to them. But he deliberately left clues and designed the whole setting around the idea that humans were not only once part of this world, they werealso aware of the flooding phenomenon.Theres this boat in the tree in the beginning of the film [] to suggest that its not the first time that this flood has come, he explains. Its kind of a recurring occurrence. And so my idea was that the people were aware of that, or at least they had some warning. They probably left somewhere, and theyre somewhere still in this world.Once the animal gang realizes how a rudder affects the movement of their rickety sailboat, they steer it from place to place, including toward a series of towers in the far distance. While most of the flooded landscape is made up of jungles and forests, they eventually come across an abandoned city. Zilbalodis says the whole city was designed with the idea that the humans were well aware of the flooding phenomenon.Theres some contraptions designed to withstand the flood or to bring stuff upward, he said. These towers, the goal that the characters are heading toward theres some symbolism about people going there to escape from floods, and building upward.The original idea for Flow was a short film that Zilbalodis created in high school. In that version, there werent even any hints about the humans. But for the feature film, he wanted to branch out not because he was interested in the world-building, necessarily, but because having interesting architecture for the animal characters to navigate would lend itself to deeper character moments.I dont start with the world, Zilbalodis said. I start with the character and the relationships, and then I think about what kind of place would be best suited to convey these ideas, and to have some conflict occur where they have to make some decisions, where different characters react in different ways. I start with the character, and then I build the background around that.Flow is now in wide release after a limited theatrical release in some cities.