The last part is where there's the group of the hero and his friends, and they slowly get left behind to stop the enemies in pretty stupid and contrived ways, usually sacrifical ones, to let the others escape. In the end they all die (or SEEM to be dead! Plot Twist for next part of the scenario!) but the hero is safe.
I mean... I don't want to question wether or not this part was necessary. The goal the script-writer probably had in mind was that to leave some important characters off screen for the next part of the plot, so he could focus on new/other characters. It's understandable and I agree with this choice somehow. Yet I've seen things like this happen so, so, so, so, so many times in Movies, Animes, Mangas... maybe it's because of the fact that I'm old and that Iv'e seen so many things that I kinda became more demanding, it's now harder to surprise me or satisfy me, but it all felt very boring and cheap to me.