The fourth game in the series, released for the Nintendo DS in Japan during 2009, but has yet to be announced elsewhere. It is, chronologically, the first game in the series, in which Layton stumbles upon a mysterious, dark and foggy town known as Mist Halely, where there are legends of a great, shadowy giant who protects the region whenever his flute is used to summon him. However, recently, the figure has turned against the village, and it is up to the Professor, a young boy of the village named Luke Triton heavily involved in the legend of the Specter, and a former colleague named Emmy Altava, to figure out why the ghost has changed as it has. Together, they investigate the village and the Specter's Flute, and, while doing so, solve another 170 puzzles. The game also includes an RPG called London Life, which was co-developed by Brownie Brown.
Source: Wikipedia, "Professor Layton," available under the CC-BY-SA License.