But after the apparent victory that closed out the Second Act, the Third Plot Point now forces a crisis—in both the plot and the character’s arc.
This point of crisis is the result of a reversal enacted by the antagonistic force. The protagonist thought he had the bad guy down for the count, but the baddie’s got one more trick up his sleeve. Usually, this reversal is accompanied by a completely unexpected (although, of course, not unforeshadowed) revelation.
Sometimes this revelation will be a plot twist, but often it will be nothing more than a sudden and full understanding of the protagonist’s Lie-empowered weaknesses. It’s this new information, as much as anything, that lays your protagonist open for the final blow. He’s so stunned he can’t even fight back.