Regensburg is looking forward to the upcoming German Catholic Day. 100,000 visitors are expected. The anticipation is cut short when a monk's body is found. Finding place is the substructure of the stage, which is set up for the opening service. Inspector Lucas and her team immediately start investigating, because one thing is clear: the opening must not and should not be postponed. Her first lead leads her to the influential "Exercitus Sanctus Jesu" order, which is controversial among lay Catholics - mainly because of its opaque banking transactions. The monks of the order, under the leadership of the Superior General, are hiding something, it becomes immediately clear. While the investigators are researching on site, the situation worsens.
In an anonymous email, the cancellation of the opening service is requested, otherwise there will be a catastrophe. The connection between the dead man on the cathedral square and the blackmail is obvious. Ellen Lucas, who makes no secret of her rather church-critical attitude, gets into a fight with Boris Noethen.Because he is trying, not least out of religious conviction, to prevent a possible cancellation of the Kirchentag, which is in the spirit of Andreas Schneiderhahn, the organizer of the Kirchentag. Since the blackmailer's email also calls for the opening of all church property for refugees, a group of Catholics who are involved in church asylum come into focus. With the help of Tom Brauer, Ellen Lucas finds out that Martina Heise, a woman from this circle, definitely has a motive to take revenge.
But new suspicions also arise in relation to the "Exercitus Sanctus Jesu" order, and Brother Peter, a monk who was very close to the dead man, disappears. Then, in another anonymous email, no less is demanded than the distribution of the entire church property to the poor. An attached quote from the Gospel of Matthew is deciphered by Inspector Lucas and puts her on the right track. But it's about much more than a theological riddle, because the blackmailer is in possession of a large amount of explosives.