Harley must rescue Ivy from the clutches of Scarecrow, who’s trying to harvest her pheromones to make a super toxin that turns plants into sentient monsters.

In the season finale, Harley has her final showdown with the Joker, when [spoilers] [spoil] [spoilers]. Will they [spoiler]? Maybe. But you can bet they [spoiler]!

Harley gets an invite to the Legion of Doom’s prospective members party, but Ivy discovers that it’s Lex Luthor they’re really after.

Now a member of the Legion of Doom and The Joker’s equal, Harley finds herself spending time with him. Will she slip into her old ways?

Determined to become one of the vaunted Legion of Doom, Harley attempts to make a big splash by crashing one of their criminal enterprises with the help of her BFF,…

Lena’s ex-boyfriend, Jack Spheer, comes to National City to unveil his big breakthrough in nano-technology, which has the potential to eradicate all diseases. Lena asks Kara to attend Jack’s conference…

While a new villain is under arrest at the DEO, Supergirl uses him to try and understand who is responsible for the recent attacks. Meanwhile, Andrea and Lena think back…