The scientist makes a rope ladder and climbs down into the well to search for the key
Barney, at the top of the well, chews the rope to try and trap the scientist in the well, but makes too much noise. The scientist comes back up to see what Barney is trying to warn him about.
After fixing the rope, the scientist goes back into the well to keep searching. The last chapter is written with bad spelling and grammar, saying Barney is dead, he was a good rat, and asking anyone who may see the journal to bring female rats to the island to pay respect for Barney. Just females.