It's Valentine's day, and outside of the assassins trying to kill her (only to get killed themselves) Harley is all alone, and a little depressed. But after her a pep talk from her stuffed beaver (telling her she can't give all her attention to her pet beaver, HAR HAR) and some good news that she got the job at the elderly home, Harley decides to stop feeling sorry for herself and go out to a singles bar, but not before noticing a plant Ivy left for her, with berries Harley decides to snack on before she leaves.
Problem with eating berries from a plant given to you by Poison Ivy is, well... the berries are probably going to do something, and that something is making everyone Harley passes to fall in love with her... so when a prison bus driver crashes, and a bunch of killers all fall in love with her... Hijinks ensue!
With a gang of murderous love candidates chasing her, Harley takes refuge in a closed home improvement store, while telling the manager (who also falls in love with her) to hold off the creeps while she finds the gardening section. Well, the manager doesn't last long, but that's okay, because Harley has decked herself out in an arsenal that would make any day laborer jealous, and gets to killin'.
After all but one creep is left, Harley figures out that it was the berries she ate that caused everyone to fall for her, but the berries are still having an effect, as the lady cop waiting outside to arrest her, decides to kiss her instead, and off Harley goes, running back to her apartment.
When she gets home, Harely decides to launch the plant Ivy gave her out of a slingshot, and far away from her. Big Tony shows up to pay a visit and get his flowers he gave her (after blowing it with Queenie) back, telling Harley he's going to fight for Queenie's love. Harley gives back the flowers, and a special "breath mint" and wishes Tony luck, while she decides Valentine's day is a shitty holiday that makes single people feel bad, and people in relationships spend a fortune to prove their love with material crap. GOOD RIDDANCE. Also, everyone loves Big Tony now.