Katrielle "Kat" Layton is the protagonist of the upcoming Professor Layton game Layton's Mystery Journey: Katrielle and the Millionaires' Conspiracy. She is the daughter of Professor Hershel Layton. Katrielle is described as being a "riddle-solving detective", who takes on various cases in London. She is assisted by a talking dog named Sherl. This page is a . You can help the Professor Layton Wiki by expanding it.