The Holy Grail. Some familiar gnome confirmed?
Maybe they will reveal that the note in front of his shop in Novigrad was fabricated and in reality he was kidnapped by a bunch of people searching for the Holy Grail, so he could lead them to the person he sold it to, who just happens to be in Toussaint. On the way he manages to send a message with plead to help that reach Geralt, who then travels to Toussaint to save his old friend from certain doom and get himself involve in an ancient conspiracy as a result.