Abstract: A pick-proof lock is provided which is rendered difficult or impossible to pick not by virtue of any additional structure or apparatus but due to the intrinsic nature of the tumbler construction wherein all of the tumblers in the row of tumblers are contiguous with adjacent tumblers so that the tumblers may not be individually set by using a pick and the equivalent of a tension wrench because there is no stationary shear plane in the direction of movement of the bolt for the tumblers to be set on.