Light exposes what was hidden, and the speaker wants the reader to see it. The poem opens with a "shadow play," a show of illusions that is now being stripped away. The "final exposure of all lies" suggests a moment of reckoning, when pretending no longer works.
The second stanza says everyone realizes they are "locked," meaning trapped, and anyone who looks around is shocked. The poem never says what the lock is, so readers can fill that in themselves: habit, deception, a false way of living. Then the imagery turns on itself. More lights should mean less darkness, yet they make the shadows sharper, so the truth becomes clearer and more uncomfortable.
The speaker sounds urgent, almost accusing, and the exclamation marks add to that. The last couplet shifts the focus inward: outside answers have all been false, and the only honest one is inside you. The mood is tense and stark, but it ends with a note of personal responsibility and, perhaps, a way out.