From CHiPs Online:
Ponch, Bobby, and Webster chase an explosives truck that caused an accident. Someone in the back throws out a hand grenade which makes Webster's cruiser flip over. Ponch and Bobby go undercover as hard-core bikers to investigate at a local motorcycle grand prix that Bruce is racing at. Soon, Ponch and Bobby arrive at their third biker bar looking for the bad guys. Ponch knows the waitress and agrees to meet her to get information. Soon Ponch ends up in a small bar fight and leaves.
After visiting Bruce at the track, Ponch meets the waitress at the park. The next day, Ponch and Bobby are back in uniform when a call comes in to Central from a trucker. He is forced to stop and his truck is hijacked. The truck ends up to be carrying a volitile experimental chemical called RNI.
Later, Ponch and Bobby are undercover again and warn the bar owner and waitress about the danger of RNI. Ponch gets a weird feeling when one of the racers drops out and one of the bad guys joins in. Meanwhile, the waitress discovers that the bad biker guys have been storing RNI in the bar's storage room.