Ask not why you were imprisoned. Ask why you were set free.

A man has only three and a half days and limited resources to discover why he was imprisoned in a nondescript room for 20 years without any explanation.
Oldboy keeps every mind human — it fights its subject at zero distance. The story fights on E8 of the E0–E14 reality ladder.
Films fighting at the same level of reality, about the same things.
The same preoccupations examined at another scale — one mind versus a nation.