As Gules tells you, Canker has a camp somewhere in the middle of the forest east of Semine. Keep heading east from Semine and you'll enter a forest. Here, you can find Canker's camp in the middle of the forest near a small water body. Wait until past midnight to make the quest easy.

Follow the bandit's treasure map to their stash, and cash in on what they were hoarding to get a lot of money.

The Vidlak Bandit's Map is likely one of the first you'll encounter in Kingdom Come: Deliverance 2, and you'll quickly realise that medieval map makers really weren't up to snuff. You get this map during the Lackey quest,