Free Frennedan from his cell

This unmarked minor quest takes place in chapter 1 of Baldur's Gate II: Shadows of Amn and Baldur's Gate II: Enhanced Edition.

Upon reaching the second level of Irenicus' Dungeon, the player can find a cell in which a commoner named Frennedan pleads for his freedom. His key can be found in a trapped chest outside the cell, along with Scrolls of Knock, Invisibility, Blindness, Protection from Electricity, Color Spray and Blur, Bolts +1, Arrows +1, Bullets +1 and a Cursed Scroll of Foolishness.

Frennedan is actually a greater doppelganger in disguise. If the player does release him, he immediately turns on the party when next they are in combat or after a few minutes have passed.