Go to the processing room. Get stuck in the trap door at the far right of the room (do this by clicking enter on the door)You will be in the metal room. Go down the conveyor belt and jump on the pipes you see there then jump up on the platform and get the ears.
Crusher should be standing on a car and beside the car is a crane climb up the yellow thingy and there's the crane. Click the levers and turn the magnet off. Than come down and climb up to the crane again and turn the magnet on. Then click
on Crusher to handcuff him (go to the scientist to get hand cuffs).
Lead him to the wet spot. Where to find Ratman: Go to the park and go inside the bathroom and go inside the sewer and use the circle thingys to drain the water and undrain them with the circle thingys and stay on the left of the sewer and enter the door.