If you were thinking of a different series, "The Missing Map" is also:
The plot centers on , the "Fifth Turtle," and his older brother Walt . [S3E40] The Missing Map
The episode features a rare sequence where Michelangelo walks the boys through a convoluted path to ensure they can't easily find the lair again—showing the Turtles actually do care about security. If you were thinking of a different series,
The episode features the Rat King , who often appears in these more "logistically" focused Season 3 episodes. Other "Missing Map" Media the "Fifth Turtle
The episode "The Lost Mine" (often associated with missing maps or documents) where Poirot investigates a murder linked to a missing mine map.