With the transformation from engineers to pilots, the ladies must fight the memories of their ancestors in order to keep their focus on finding the defensive weaponry that goes with their bots. The city holds the key to the weapons, but the bots are on the outside of the gates and the caches are on the inside.
Each ancient pilot knew where the weapons had been buried, and those memories are now pressed into service as the engineers break through the city gates to get what they need to save their own people.