Irmingast is the main antagonist of the book Die unwahrscheinliche Reise des Jonas Nichts. He is a false priest at the manor Wunderlich.
In the world Fantasien, he is known as the sinister Shepherd, enemy to the Empress.
He arrived at Wunderlich 13 years prior to the story, claiming a wheel on his carriage broke. The deeply religious Alma asked him to stay as her spiritual counsel and Irmingast had stayed at Wunderlich ever since. It did not last long until Irmingast discovered Wunderlich's secret. Clara and Alma, who had lived at Wunderlich since their childhood had invented a fictional universe accessible through a cabinet. The children had seven puppets (wich were given to then by the baron), who were real people inside Fantasien instead of figures. With their fantasy Clara and Alma had created a backstory for every character. Irmingast, wanting to seize control of Fantasien, stole one of the puppets, the monk Faramund, thereby gaining control over the person Faramund inside the world in the closet. As one of Clara's characters, Core, had made a prophecy claiming that a boy born in the hour of her death would be his undoing. After her death Irmingast had Faramund capture all boys fitting to the age. These boys are known as Faramunds pilgrims, brainwashed servants of Irmingast who serve him. At Fantasien Irmingast was known as The Shepard, living in his black monastery built in the ruins of the old capital Callamar which had been abandoned. He also took many of Fantasien inhabitants captive and forced them to work in quarrys to harvest the stones used to build his monastery.
During all this time, Alma, who in Fantasien is the empress, had no idea that her support in the real world was her enemy in Fantasien.
When Jonas Nichts, a 12 year old boy from a farm, learns that he has the manor Wunderlich from the countess Clara Fink, he is picked up by attourney Peregrin Aber and the two travel to Wunderlich. When they arrive there at night, the door is opened by the cook Tabbi. After a short conversation at the entrance hall they are interrupted by Irmingast who descends from the stairs. Jonas immediately takes a disliking to Irmingast. When he says to Irmingast that he is thirteen and not twelve years old (the mute servant Ruben gave him a piece of paper which said that he should tell anyone that he is twelve) Irmingast does not seem to believe him although he does not ask further.
The next day, when Clara's last will is read, Irmingast is there with Countess Alma, cousin of the deceased Clara who deeply hates Jonas because he inherits the house she was supposed to get. when Alma insults Jonas, Irmingast calms her down a bit. As soon as the will is read Alma storms out of the room. Irmingast remains in thoght.
Days later, a chandelier drops from the ceiling, almost crushing Jonas and Tabbi. Though Tabbi acts like it was an accident in front of Jonas she secretly wrote a letter to Peregrin Aber, claiming that she fears for Jonas' life. When Peregrin Aber reads the letter he thinks about people who have a motive for killing Jonas. As Clara's will said that Alma would be only allowed to remain at Wunderlich as long as Jonas lives (added as a way to ensure that Alma doesn't harm him to get the manor) Peregrin thinks that Alma is not responsible and as Irmingast is on Alma's side, would not do something that would harm Alma. However, after sending his secretary to make some inquiries he finds out that Irmingast is no priest as he claims. Aber returns to Wunderlich but to his distress he is told by Tabbi that Jonas and Ruben are gone. While being outside in the yard, shots were fired at them with a rifle and they disappeared after. Unbeknownst to Tabbi and Aber, Ruben and Jonas escaped to Fantasien through the cabinet.
Irmingast is not seen for a long time in the book until Jonas' arrival at Callamaar, where wants to find Ruben who has been taken by Faramund and been brought to the Shepard into the black monastery.
With his allies, Jonas witnesses the Pilgrims of Faramund gathering on the vast place before the monastery. Then the heavy stone gates of the monastery open and the Shepard comes out, riding on a donkey led by Faramund. Irmingast tells his pilgrims that the time has come to attack Kanaria, the castle of Empress Alma. To show his strength, he uses magical powers (he aquired through the puppet of Faramund) to destroy the old palace of Callamaar. He then sends his army of pilgrims to attack and conquer the castle, making his conquest of Fantasien complete.
Attack on Kanaria
The attack on the castle laves Kanaria in ruins. Irmingast takes up residence at Kanaria. When Suleman Mond and his rebels attack the castle Irmingast uses his power to blow up many of them. He mortally wounds Krempel in the progress (though he is later healed by Jonas). The rebels realise that they have neither the power nor the soldiers to stop the Shepard and retreat.
However, after Jonas realises that like Clara (Alma lacked the imagination) he is able to shape the world with his fantasy, he returns to the castle accompanied by all the friends he made on his journey. As Ruben broke the Faramund figure earlier (stripping Irmingast of his power and killing Faramund), Irmingast is without power, only able to scream at the masses coming closer to his castle. Screaming that the castle and Fantasien belongs to him, he returns inside the castle. However, Jonas uses his experience and one of the spiders from the Spider's palace( where Jonas learned the truth) Jonas covers the whole castle of Canaria under spider webs, trapping Irmingast (and Alma) forever inside.