The Mystery of the Decades-Old Mystery (S02E10)

S02E01 The Mystery of the Missing Pimento Cheese Recipe S02E02 The Mystery of the Mammal Island S02E03 The Mystery of the Strawberry Patch S02E04 The Mystery of the Adventures of Pon-Pon S02E05 The Mystery of the Marauding Mascot S02E06 The Mystery of Meg's Extremely Violent and Inappropriate Musical S02E07 The Mystery of the Golden Lungs S02E08 The Mystery of Dr. Marjorie Frost S02E09 The Mystery of Lance's Lesson S02E10 The Mystery of the Decades-Old Mystery