“Fits, doesn't it?”

To expand this to the full sentence the word "fits" is expressing everything below that is in bold

All the information we have and everybody's actions all make sense, doesn't it?

I hope you do jigsaws as this analogy will work a lot better if you do :)

Imagine the story to be a jigsaw, all the clues are jigsaw pieces, one very important piece was missing so none of the other pieces fitted together. They have just found the last piece and everything now fits.

“Fits, doesn't it?”

To expand this to the full sentence the word "fits" is expressing everything below that is in bold

All the information we have and everybody's actions all make sense, doesn't it?

I hope you do jigsaws as this analogy will work a lot better if you do :)

Imagine the story to be a jigsaw, all the clues are jigsaw pieces, You have lots of pieces, some are together making a picture, but there are some gaps still. This new piece fits nicely into one of the gaps filling in more of the picture.

Thanks to @AC for reminding me of this.