The 2003 Teen Titans series takes something of a 'monster of the week' format, as in most episodes, the Titans conquer a new villain. The cast of foes pose varying degrees of challenge to the young heroes, and this typically informs the seriousness of the episodes. From the mind-bending yet amusing Mumbo Jumbo to the more formidable Doctor Light; from the massive Plasmus to Killer Moth; the Titans heroically subdue each threat to Jump City and send them off to prison. Other times, though, their enemies are more personal and complex. The arrival of Starfire's sister, Blackfire, is celebrated until it is revealed that she has nefarious motives. The wayward hero Terra is encouraged to become a Titan, but insecurity pushes her against the group and into the dark side.