In Professor Layton and the Miracle Mask, Angela Ledore, an old high school friend of Layton's, calls Layton to the town of Monte d'Or to investigate the self-proclaimed Masked Gentleman who has been performing terrifying 'miracles' using the power of an artifact called the Mask of Chaos.
In Professor Layton and the Curious Village, Layton and Luke are called by Lady Dahlia of St. Mystere to investigate the will of the deceased baron, who had mentioned an artifact named the Golden Apple for whom the bearer would be entitled his entire fortune.