*puts on a Transylvania Polytechnic Faculty pin*
So, at the end of the last big arc, Baron Wulfenbach tried to invade/destroy Castle Heterodyne to stop Agatha, or more specifically The Other, who is inhabiting Agatha's body, from eventually enslaving or destroying Europe. In the end, the Castle and the loyal Heterodyne people, plus the Jaegermonsters who returned to Agatha's side when they found out she was the True Heterodyne held off the Baron's combined forces until he stepped in personally, flying into the middle of town and setting off a time-stasis bomb. Agatha barely managed to escape at the last moment, shoved through a portal in the basement of the Castle. However because of the stasis bomb, she comes through the other side of the portal three years later.
In the meantime, the Baron is stuck in Mechanicsberg with the rest of time-stuck people so Gil has taken over the empire. He has been apparently running himself ragged, trying to free people from Mechanicsberg, locate Agatha who he believes is alive and free and run a very unstable empire, as many minor houses saw the loss of the Baron as an opportunity. Not helped by the Storm King being a strong contender, and after Agatha himself. Gil's become even more Mad than ever. He did manage to pull Commander Vole out of the time field... Since Jaegers are very tough and long lived, he is able to survive the 'thawing out' process, where as most people suddenly aging three years in under an hour kills them.
Agatha in the mean time has been reunited with her inner circle that escaped Mechanicsberg. Jaegermonster Dimo has been promoted to General and been running a harrying force against the Empire, trying to stay out of their hands. Helped somewhat by Zeetha and Higgs having a (not terribly) secret relationship. Agatha and company decide to get out of Europe and make their way to Paris icognito, hoping to find a way to Free Mechanicsberg, get The Other out of Agatha's head or at least lock her up there permanently and generally keep everyone from capturing her for their own purposes. They decide to take the train there under cover since they are a neutral force.
On the way they meet the Lady Selinkov who falls in with their group. The train is attacked by a spark with a giant clank and the bear warriors, under command of the Storm King. Despite trying to fight them off, they fail and are forced to flee in one of the train carts, transformed into a dirigible and head back to the train's monastery home. General Dimo is injured and captured by the bear warriors at this point. At the Monastery, the Storm King shows up and pressures them to submit to him. Meanwhile his agent Lady Selinkov who we found has been part of an engineered plot by the Storm King forces a monk to lead her into the vaults where dangerous things are kept, trying to find something. While she fails to find what she was looking for and gets killed in the process, she winds up freeing a sentient, greedy and crazed locomotive clank that starts rampaging through the Monastery, eating everything as it goes. This forces the brothers to accept the Storm King's help in destroying the monster, as well as Agatha's.
In the mean time, Dimo is brought before the Bear King because they smelt the Master on him. The King gets Dimo to lead them to where the Master is... and the big surprise this week being that the Master is Krosp, not Agatha like everyone was assuming. I think that brings the major points home...