The Darkness Between Door is the third story in the Doors series. It is full of action and adventure as Derry, Cally and Grandpa Mike continue their search for clues to discover what caused the Armenti Empire to fall. It is certainly my favorite of these great stories. Nyf (an AI) and our heroes' next trip is to the vacation planet, Rustgevend, where they will find many dangers. Geron has created some interesting worlds in the series and this one is unique. It is filled with a variety of different species from the old empire. As always in Geron's stories the writing is excellent and the characters engaging. I recommend this story highly, but suggest you start with the first in the series.