What's up with Lois: Lois returns from Europe and shakes things up in Smallville in the process. While diving she hits her head on the board, but a mysterious stealth swimmer named Arthur Curry (a.k.a. Aquaman) saves her before Clark can. Soon she falls for AC, despite some initial reservations about him.

What's up with Clark: Clark's first day in college doesn't start off well when he is tardy for class. Then he defends Lex when his teacher, Professor Fine, compares Lex, who has succeeded at an early age as head of LuthorCorp, to some of the most devastating world leaders in history. Yet Clark's courage impresses Fine, and Fine wants Clark to work for him as a research assistant.

What's up with Chloe: Chloe helps Clark investigate AC's background. Clark is suspicious because of his amazing swimming speed, but Chloe just thinks Clark is jealous of AC.

What's up with Lex: Lex is developing a new weapon, "Leviathan." However, it has a harmful effect on fish and water. AC knows this, and Lex soon captures him. After AC escapes, he vandalizes Lex's marine center before Lex can unveil the weapon to the military. Lex doesn't like how Clark is taking AC's side on the environmental issue, but Clark and Lex remain friends.

What's up with Lana: Lana is not too happy with the way Clark treats AC when he first meets him.

How it ends: Clark accepts Fine's job offer. The professor's goal is to expose LutherCorp.