Zed's Dead, Baby. Zed's Dead.

Run southwest along the main road, and up the wooden steps to the locked door above Zed’s stall. There are sounds of commotion coming from inside. Head back downstairs, climb the ladder by the woodworkers, then ascend to the roof ledge before stepping to the edge and leaping across to Zed’s roof. Enter through the attic door.

Drop down into the bedroom, where you can examine the body of Zed—he’s quite dead. Descend via the interior steps, and you intrude into a conversation between two bandits. They have one of the cards you seek, but can’t find the other. Draw your sword and pulverize them.

Once the intruders have been defeated, inspect the corpse of the bandit called Ringo, and you can gather the first Gwent card you seek, along with the keys to this abode (allowing you to unlock the door you couldn’t access on your way here).

Now start to methodically check the room for the ledger. There are a couple of scattered chests, but the area of real interest is a scratch mark under the stairs. Use Aard to remove a small false wall beneath the steps, allowing you to pry open a chest and gather the ledger. Now return to Zoltan.

Speak to Zoltan about the cards. The ledger shows Zed’s been selling cards to somebody called Caesar Bilzen, and another called Ravvy. Ask who these fellows are (Cleaver’s clerk, and someone Zoltan doesn’t get on with, so they must be visited alone). Your two new objectives appear, and can be completed in either order (though it’s better to visit Ravik first).