Ep 10. Disciple

In Smallville season 9 episode 10 titled "Disciple," former queen of the underworld Alia appears in town and seeks out Clark's help in defeating the new ruler of the underworld, Zod. Alia wants Clark, who she views as her disciple, to aid her in killing Zod and taking over the underworld once again. Clark is hesitant to help as it goes against his moral code of not killing anyone, but Alia manipulates him by using memories of his father to convince him to help her.

Meanwhile, Lois is investigating a story about a vigilante on the loose in Metropolis who is attacking criminals. The vigilante is revealed to be a young girl named Cassie who has been trained by her father to fight against crime. Lois tries to convince Cassie's father to stop putting her in danger, but he is determined to make her a hero in her own right.

As Clark continues to train with Alia, he begins to realize that her intentions are not pure and that she is using him. He tries to back out of the plan, but Alia threatens to harm those he cares about if he doesn't follow through. Clark reaches out to Oliver for help, but their plan to stop Alia and Zod goes awry and Clark is left to face off against them alone.

In the end, Clark is able to use his powers to defeat Alia and Zod and once again save the world. However, he is left with the realization that he needs to become stronger and more in control of his powers if he wants to continue to protect those he loves.