"Do you really wish to know?" Spoilers from the books and/or games to follow!
No evil can survive the Holy Fire! The Holy Fire enlightens, burns and cleanses! Behold the flame of grace and mercy! Special pyre for you, freak - nice slow burning. You'll beg for mercy in all the voices known to you, like the others of your species.
In those days rampant persecution and the smoke of a hundred pyres choked Novigrad's air. This grim climate provided cover in which a great many bloody butchers built comfortable nests for themselves. Drummed-up conspiracies, mass arrests and show trials resulting in group executions were the favorite building blocks.
Caleb Menge, the fanatically ambitious commander of the Church of the Eternal Fire's Temple Guard, was one such opportunist, his moment of triumph coming when he unmasked his superior, the former Temple Guard commander Chappelle, as a doppler in disguise.
Geralt first saw Menge lighting Chappelle's pyre in Novigrad's main square and had no doubt that, for this man, the appellation "fanatical whoreson" was too mild by far.
Which is why I was not pleased - to say the least - when an unfortunate turn of events led to my capture by the agents of this vile man.
The paranoid executioner never set a foot outside his fortified headquarters without a crowd of armed guards to accompany him. Knowing my life was on the line, my friends decided to pursue a risky plan to infiltrate Menge's offices - their only hope for a face-to-face meeting with the man.
Menge only confirmed Geralt's initial impression of his bestiality upon closer acquaintance.
If Geralt peacefully talked to Menge and didn't ask about the treasure:
Luckily Triss' dagger ended this madman's life and rid the world of one the more hideous monsters to ever walk its surface.
If Geralt fought the witch hunters or asked about the treasure:
Luckily the witcher's blade ended this madman's life and rid the world of one the more hideous monsters to ever walk its surface.