Kara and Clark continue operating together in National City before he decides to return to Metropolis. When they encounter Corben, who has turned into Project Cadmus' prototypical cyborg, his Kryptonite-based powers pose a serious threat. The DEO deduces that there is a mole who smuggled the kryptonite out. During a subsequent encounter with Corben, another Metallo prototype goes on a rampage in Metropolis without opposition. Alex finds the mole, but he is killed by Cadmus's leader, a scientist who intends to destroy aliens. Winn builds anti-kryptonite gear for Kara and Clark, who manage to defeat the Metallos with the help of Alex and Hank. Kara promises the Cadmus leader she will find her. Hank entrusts the remaining kryptonite to Clark, who returns to Metropolis. Meanwhile, Cat introduces Kara to the latter's new boss, Snapper Carr, who does not like her and refuses to give her an assignment. Cat advises her to solve the problem herself and announces that she has decided to leave CatCo, leaving James in charge. Kara manages to prove her value to Snapper, who agrees to teach her. At the DEO, the alien man regains consciousness and attacks Kara.