The release trailer contains minor spoilers, so to understand the reasons why Remi ends up being interrogated, you can watch the story trailer at the link.
Hell is Us is set in the fictional country of Hadea, torn apart by war between the Palomians and Sabinians, where a mysterious Catastrophe also occurred. Remi enters this chaos, fighting Hollow Walkers in search of his parents, but gradually gets drawn into something much bigger.
The game does not offer hints or direct guidance: players must explore the environment, communicate with NPCs, and collect clues to advance the plot. There are also Dungeons full of dangers and puzzles that need to be solved to progress further.