How does it end?

Now that Halo Round the Moon is finished I have begun planning the fourth story for Maliha Anderson and William Albert Valentine Crier (known to his friends as "Bill", and to Maliha as "Valentine", his least-favourite forename).

When asked whether I'm a planner or a plotter, as I may have mentioned, I'm somewhere in between. But there are key things that I must know. And the most important of those things is how the story ends. If I don't know how it ends I can't write because I don't know whe...