The Hook and Ladder is one of the greatest trick plays in any playbook. It involves incredible timing and perfectly performed maneuvers by multiple individuals, but can be a phenomenally successful play when all the moving parts come together correctly.
The QB must deliver the throw to the In route before he gets too far across the field. The WR running the Shallow Cross must time his crossing route so that he is running underneath the In route immediately after he catches the ball. Once caught, the In route has to quickly secure the ball, and then pitch it backwards to the shallow crosser. The defense will have been moving inwards towards the original receiver, and will be caught off guard when the shallow crosser receives the pitch and is sprinting outward towards the sideline.