Direct answer
Objectives follow journal display order. Some depend on your choices; follow the active objective in the game.
Result
Novigrad, the most cosmopolitan city of the North, attracts its fair share of oddballs and eccentrics. One of them was a merchant dealing in unusual goods. While talking to Geralt he spied some witch hunters approaching and fled at once. Still interested in the secretive merchant's secret wares, Geralt decided to hunt him down.
