The Witcher 3: Wild Hunt (2015)

Carnal Sins gives Novigrad room for a grim detective story away from the hunt for Ciri. The interest is in following evidence and questioning an apparently tidy explanation, rather than clearing another monster nest. Follow Dandelion's Cabaret thread when it is offered and let the investigation unfold. This is a base-game secondary quest, with disturbing material and no expansion purchase required.