Why the hero must save the day

It’s always disappointing when a story that begins with so much promise falls in the final pages.

This happened recently in a trilogy I was reading. The first book was great—it worked well as a complete story, but with enough unanswered questions to encourage me to keep reading. The second book meandered a little, but I was able to let that pass—it was setting things up for what promised to be gut-wrenching finale. The hero had gone through so much inner turmoil, but now he was in an impossib...