Back to Velen
Continue on the path east from the Boatmaker’s Hut and you’ll come to a bridge being guarded by 3 Bandits. They demand a toll to let you pass safely over the bridge.
You can either fight them and kill all three of them or show them your Medallion. One of them recognizes that it’s a Witcher’s medallion and they wisely decide to let you pass.
Whether you fight them or convince them to let you pass use your Witcher senses on the other side of the bridge. Follow the footprints to a hidden chest in the weeds under the bridge. Inside you’ll find a few Crowns and a couple of Diagrams.