The title is a play on the phrase "highway robbery."
The Road Runner is running down the highway and his wake is rattling objects on the side of the road. When he passes Wile E. Coyote, the gust of air pushes a cactus into Wile E.'s backside causing him to hop into the air howling. Later he chases the bird around and around a junk car, kicking up a cloud of dust, and the Road Runner disappears. Wile E. examines the car, but it suddenly starts and runs over him. Road Runner pops up behind the steering wheel, turns the car around, and crashes it into the coyote against a rock face.
Wile E. uses a giant rubber band as a slingshot. It flings him into a few boulders, then the Road Runner ducks as he sails over, crosses a canyon, and smacks the opposite wall, before falling to the canyon floor and making an accordion of himself.
He rigs a sail to a skateboard, then uses an electric fan to blow wind in the sail. Using this he nearly succeeds but the cord pulls out of the socket and he coasts off the edge of the canyon again.
He builds a bomb with dynamite and an alarm clock, and puts it inside a big egg shell. He places the egg in a nest on the road and when the Road Runner comes he dutifully sits on it. It soon hatches, and out walks the alarm clock with a road runner head on a spring on top of it. The clock walks over to the hiding coyote and promptly explodes.
Lastly, he straps a big rocket on his back as he's riding a motor scooter. However, when he lights the rocket it sends him up in the air, nearly into space, but what goes up must come down.
Wile E. howls like a real coyote after getting slapped on the back by a cactus. This is the first and only time he howls.