When Worlds Collide is the eighteenth episode of the fourth season. It was released on 16 May 2008. When one of Charlie's friends, a scientist at the university, is arrested for terrorist activities, it puts him at philosophical odds with Don. And as he works to prove the man's innocence, his beliefs may jeopardize his career.
[This appears on the beginning of the episode] 783,350,200 online research documents 41,000 gene loci in rice 112 designer viruses 2 kidnapped men