The school unknowingly uses red kryptonite in the class rings and its effect on Clark stuns his friends and family as he turns into a rebellious and dangerous teenager who begins to turn to the dark side. Jonathan and Martha scramble to find the truth behind Clark's behavior before he exposes his true identity, while Lana finds herself drawn to the "new" Clark who declares his love for her. Not since Metamorphisms has there been an episode this good. This is the original red kryptonite episode and is probably still the best. A major problem with using red kryptonite is that the writers have to come up with something new and creative to do with it, which is quite hard. I guess that's why you don't see them too often.