Source plot synopsis — includes the ending
Yu and Kay successfully flee through the flow bridge that connects the planets and begin a new life on Source together, but as their floating island crumbles, their ship is damaged. They begin to explore Source to work on repairing it, and realize that the Apiary had colonized Source at some point. There is also a mysterious spreading contagion called Rust. After the Apiary sends drones after them, the pair decide to video call Yu's mother, who reveals Source's strange floating island state is the result of Apiary's disastrous experiments to harvest Flow and study Rust only 20 years ago. After Kay's pendant opens a door on Source, they realize that Kay's parents probably died on Source during that incident.
Eventually the pair is contacted by Lord Ozias, Yu's assigned spouse before she fled with Kay. Ozias announces his intention to come to Source and bring Yu back – and wipe their memory if they refuse him. The couple decide they have only one option: sever the connecting bridge from Source that allows the Apiary to travel there. They must repair their ship and fly into the source of both Flow and Rust.
The game has several endings. If Yu and Kay have misgivings about severing the flow bridge, they decide to make a last stand against Ozias' drones, which eventually capture them. The two of them are shown being brainwashed and memory wiped but eventually content in their separated assigned lives on Apiary. If Yu and Kay decide to close the flow bridge, one of them is blasted with Rust and is permanently scarred, but they succeed in closing off Source from the Apiary and can begin their lives on Source without fear of the Apiary's interference.
Sources and content license
Source and revision history ↗ · Adapted from Wikipedia contributors, Haven (video game). Section headings and formatting adjusted. · Content license