After Niche carries the wounded and dazed Lag back to the Bee Hive, the Letter Bee finally starts to piece the puzzle together. He now understands what happened to Gauche, why the Marauders are so intent on stealing mail, and the true purpose of Reverse, the group controlling both. However, when he is forbidden from revealing the truth, Lag is soon forced out of the artificial sunlight and back into the world of perpetual night. Meanwhile, Reverse's plot to dismantle the Letter Bees and overthrow the Amberground government begins to accelerate. If things weren't already dire enough, the giant insect creatures known as gaichuu appear to be evolving into something new; there may be traitors operating within the Hive; and Niche's sister, who is certainly not friendly to humans, arrives to turn family drama into a full-scale siege! It all spells serious trouble for the Letter Bees, but if anyone can weather the storms and gloom of the night, Lag and his team are the ones who'll deliver.