Martin Meyer is an Imam called Husamuddin. Imam Meyer fights his own war against ISIS by teaching the Koran. He deals with religious training and his students are the inmates of the Wiesbaden prison, in the heart of Germany. Imam Meyer knows these inmates well, some of them are returning fighters, they went to Syria to join ISIS and then fled back to Germany. They all are Germans citizens, second or third generation's immigrants coming from Islamic countries: misfits, excluded, marginalized and fascinated by the words of the ISIS recruiters. Prisons always have been a fertile ground for the seeds of revenge, social redemption and hatred.