After Winslow dies, his wife Mary comes to National City to attempt to reunite with Winn. However, a new murderous toymaker threatens Winn and Mary, Meanwhile, M'yrnn asks Alex to keep a secret from Hank, and Mon-El tries to find the right time to tell Supergirl something important about one of the Worldkillers.

The third Worldkiller, Pestilence, begins striking down the citizens of National City.... including Winn and Alex. Supergirl and Imra disagree on how to deal with Pestilence, and Lena continues trying to find a cure for Sam.