Samson sits in prison contemplating and discussing his terrible situation. It's even more depressing than it sounds.
But it gets worse, when Samson receives visits from his father, his ex-wife Dalila, and a hero of the enemy, none of which cheer him up at all. In fact, these visits just make him more angry and isolated. Finally, a messenger arrives ordering him to appear at the theater. Samson refuses and the messenger stomps out.
For unknown reasons (we're guessing God), Samson has a sudden change of heart and agrees to appear at the theater. And boy does he! While leaning oh-so-casually against the pillars, he collapses the building, killing himself and, as a bonus, all the rich Philistines who are watching.