Next day at lunch, Rayli’s friends prank her, then they dare her to prank a raven they see in their tree. Rayli sneaks up to tie the raven’s claw, but when the raven gets startled and flies away, Rayli gets tangled and pulled out of the tree, then falls into the river and over a waterfall. The raven swoops in to save her, and they splash into the river and swim to an uninhabited island. The raven is angry that her wing is now hurt and she can’t fly home and she’ll miss school. Rayli is angry she was dropped in the river and can’t get home. She learns the raven is Corva, the same age as her.

Later, three pirate alligators come to bury treasure on the island. They see Rayli and Corva and chase them, who escape to an old abandoned raccoon house up a tree. They decide to stay the night there. Rayli thanks Corva for saving her, and she binds her wing. She learns more about Corva and that she plans to be an engineer like her father. In the morning, they gather materials, dodge over the pirates, and build a raft on the river in a hasty escape. The pirates start chasing them, but then complain about working conditions and go on strike.

As Rayli and Corva raft down the river, they sing about adventure. Then they stop at a small town to get supplies. There they unintentionally foil a family of raccoon con artists, who then chase them back to the river.

While rafting, a storm comes, and their raft is destroyed on the rapids, and night falls. A frog named Craw finds them drifting and rescues them, taking them home to Croaken Cove, a Cajun colony of stilted swamp houses. As they rest for the night, the frogs croak a song about priorities in life.

The next morning, Craw leads them to a steamboat landing. The alligators see them and start to pursue, but stop for a mandatory bathroom break. Craw introduces Rayli and Corva to the steamboat pilot, a turtle named Langhorne. As they embark, Langhorne patters a song about how to navigate the river/life. Later they see the raccoons onboard, who chase them off at the next landing. The raccoons decide to follow them to steal eggs from the raven’s colony.

Rayli and Corva walk to Raven Steam and ride the steam elevator up to Iron Cliff, the steampunk colony where Corva lives. Once settled in, Rayli helps Corva finish building a chariot, as they sing about collaboration. Corva’s father is impressed with Rayli’s design skills.

Early in the morning, the raccoons scale the cliff, sneak into the colony and steal raven eggs from the nursery. The ravens scramble to pursue. Rayli, Corva, and her father pursue in a dirigible. In the battle, Corva falls out, still unable to fly, and the raccoons take her hostage. Rayli flies on a raven to pursue, finds Corva, and rescues her and the eggs. The raccoons chase them, then they all run into the alligators. Rayli and Corva escape to the dirigible with the eggs.

As they fly in the dirigible to take Rayli home, Corva’s father tells her she’s a natural builder. Later, Rayli writes her college application essay about how she found her spark, and Corva writes her essay about learning priorities over grades. They move into a college dorm as roommates, and we see all their architectural projects over the next few years.