Elijah Crane was just a normal seventeen year old kid who was good at chemistry. Then an empire from another world summoned him because they wanted a hero to fight for them. They thought he would land right where they wanted him to. But the summoning went wrong somehow and he ended up thousands of miles away, in a swamp, all alone and far from where he was supposed to be. And it was the exact place the empire hated the most.
The people who found him there weren't human. But they still helped him and took care of him.
Elijah isn't really a fighter and he never becomes one either. He gets stronger in a different way, by understanding things and listening to people that everyone else called enemies. The empire wanted him to be a weapon to make all the other races bow down to them. But that's not the kind of person he turns into.
The rest of the story is about him trying to fix things, and it isn't easy. In the end the whole world changes and no race is above any other anymore. And whatever it was that messed up his summoning in the first place never explains itself. It just watches him from far away, like it's waiting to see what he becomes.