9 Clues 2 is a hidden object game much like its predecessor, with a few logic and inventory puzzles to add variety, and some investigation scenes where you must pinpoint "out of place" objects in a crime scene in order to reconstitute the actions which took place in that room. This time, the player may replace hidden object scenes with Mahjong puzzles if he/she wishes, and hidden collectibles are available for extra achievements.
Regarding the plot: "It's coming! It knows! Please.... help us..." That's the phone call that you, a Private Investigator in 1950s America, receive. Your partner Owen traces it to Mnemosyne Asylum, so you both depart to the isolated island where that institution is located. Upon arriving, you are met by doctor in charge Klaudia Krauz, who finds unlikely that anything distressing might be happening there; but her idea is quickly dispelled when a body flies out of a window... Was it suicide? For what reason? Maybe the staff or the patients are willing to reveal the dark secrets of Mnemosyne Asylum?