Honestly, this is such a great thread prompt because it drills right into a core fantasy I didn't even know I had. When a protagonist is literally boxed in, the character work has to be airtight; their escape is a puzzle of wit, resilience, and sheer force of will, not just physical strength.
I'm immediately thinking of 'The Boxer'. Yu starts as this hollow, apathetic kid literally and metaphorically trapped by his own trauma and the system exploiting him. His 'escape' isn't just winning fights—it's the slow, brutal process of reclaiming his own humanity and rage from the cage others built for him. The danger is psychological as much as physical, and watching him shatter those internal walls is devastating.
For a more classic survival trap, 'Sweet Home' and its sequel 'Shotgun Boy' are masterclasses. The protagonists are trapped in an apartment complex or a school by world-ending monsters. The escape isn't a sprint to the door; it's a grueling, communal struggle where the real danger often comes from the other survivors. Cha Hyun-soo's arc from a suicidal teen to someone fighting for a future, while his own body threatens to become the monster, is peak trapped-protagonist energy. The tension is relentless because the cage keeps changing shape.