Lex's secret experiment at Luthorcorp goes awry and causes a dangerous toxin to be released into Smallville. Those infected by the toxin, including Clark, (well at least something got him down), Lex, Lana and Jason imagine their greatest fears come true and then fall into a coma. Desperate to find a cure, Clark gives some of his blood to Lex and is stunned at what Lex does with the antidote. Mostly, but not 100 percent, I am disappointed in Season Four, so far. Also, has Lex released Lionel after placing him in prison and is turning more to the dark side? There were no redeeming qualities in this very dark episode.