Clark saved Earth from annihilation in last May's finale, but there's still plenty of danger in store as Season 5 takes off. In a storyline reminiscent of "Superman II," a pair of Kryptonian evildoers arrive looking for Clark. Making matters worse, the Teen of Steel's heroics are restricted by Jor-El, who says he must return to the Arctic - and the newly formed Fortress of Solitude - by day's end or "the consequences will be grave." As if that were not enough, Clark later faces a challenge more daunting than superhuman foes, ending the episode on an intriguing note.