In the midst of the chaos, Grandier and Madeleine return and are immediately arrested. After being given a ridiculous show trial, Grandier is shaven and tortured – although at his execution, he eventually manages to convince Mignon that he is innocent. The judges, clearly under orders from Laubardemont, sentence Grandier to death by burning at the stake. Laubardemont has also obtained permission to destroy the city's fortifications. Despite pressure on Grandier to confess to the trumped-up charges, he refuses, and is then taken to be burnt at the stake. His executioner promises to strangle him rather than let him suffer the agonising death by fire that he would otherwise experience, but the overzealous Barre starts the fire himself, and Mignon, now visibly panic-stricken about the possibility of Grandier's innocence, pulls the noose tight before it can be used to strangle the priest. As Grandier burns, Laubardemont gives the order for explosive charges to be set off and the city walls are blown up, causing the revelling townspeople to flee.