Gosalyn has spent an evening effortlessly wiping the board with Drake at a series of board games; he decides that he might be able to beat her at the Swahili version of Trivial Trivia, as neither of them speak Swahili, but as she darts up to her bedroom to fetch the game, she encounters Launchpad, who is cleaning her room and doing her homework after she beat him at the Swahili version of Trivial Trivia. Drake is unamused to discover Gosalyn's trick, but they are interrupted by an incoming crime alarm on D.R.A.T., the Darkwing Remote Alert Terminal; however, discovering that said crime involves Bushroot breaking into a botanical lab requires listening to KRYM radio. Drake refuses to let Gosalyn accompany him until she learns that friends are people you help, not people you use; moments after he leaves with Launchpad, Gosalyn reasons that since her dad and Launchpad are her friends, she should help them fight Bushroot, and promptly takes off after them.
Bushroot is collecting ingredients for his IQ2U potion, which will create sapient plants for him to befriend. Darkwing ambushes him, but he sics an army of bonsai on him and tries to flee with his pet, Spike. However, he spills the potion and is caught while trying to salvage it... just as Gosalyn arrives, landing in the puddle and causing a scuffle during which Bushroot and Spike escape. Bushroot tests the potion on a hedge, which becomes a hideous (though sapient) slime/hedge mutant named Hedgy. Gosalyn's encounter with the potion has also turned her into a slime mutant; she's happy as she is (bar her newly huge appetite), but Darkwing sets about trying to cure her. His attempts are interrupted by another alarm from the D.R.A.T.; this time, it takes reading the evening paper to see where Bushroot has struck, and Darkwing takes Gosalyn along to keep her from literally eating him out of house and home.
Bushroot has been stealing food for the very hungry Hedgy, who corners Darkwing and Launchpad. Fortunately, they are saved by Gosalyn, now calling herself Yucky Duck. During her introduction, Bushroot escapes, but not before he witnesses Hedgy melt into a puddle of green goo. After seeing her in action, Darkwing finds himself more interested in using Gosalyn's powers to find Bushroot than he is in finding a cure for her condition or even treating her like his daughter. Hurt by her dad's coldness, she runs off into an alley, where Bushroot finds and befriends her. Back in his lair, Darkwing finally finds a cure for Gosalyn's condition, but tells Launchpad it may already be too late; the mutation proceeds in four stages, namely intelligence, indigestion, insanity, and "in a puddle". If they don't get to her soon, Gosalyn will dissolve into a puddle as Hedgy did.
Back at Bushroot's hideout, Gosalyn is already becoming a babbling simpleton who devours everything she can get her pseudolimbs on; with her dwindling sapience, Bushroot is now no longer interested in her as a friend, but as a sample for cultivation to refine the IQ2U potion, and he vacuums her into a containment chamber. Darkwing arrives before he can continue the experiment, and in the ensuing scuffle, Spike gets the potion and buries it outside, where it turns the lawn into a huge woman/grass mutant. Bushroot and Darkwing are forced to team up against the lawn; Bushroot helps Darkwing escape for long enough to summon a flock of sheep to devour the mutant. Meanwhile, Launchpad's attempts to free Gosalyn succeed only in getting him trapped in the chamber with her, but Bushroot is able to free both of them. Darkwing decides to let Bushroot go free as a gesture of gratitude, noting as he leaves with Spike that he had a friend all along. He then takes Gosalyn back home to administer the cure for her mutation: a bath with plain old soap and water.
This episode includes examples of the following tropes:
- Abhorrent Admirer: The sapient lawn flirts with Darkwing and even plants a kiss on him. He's quite repulsed by her affections - mostly because he doesn't want grass stains on his cape. She doesn't take the rejection well, however, and attacks both him and Bushroot in anger.
- Awesome, but Impractical: Darkwing's Remote Alarm Terminal. Using a series of sensors strategically placed all around St. Canard, it sets off an alarm in Drake's house to alert him to a crime in progress. Unfortunately, it doesn't actually tell him where said crime is actually taking place, and he has to resort to local news reports to figure it out, making the device most redundant.
- Big Eater: Gosalyn works up quite an appetite after her transformation, eating a potted plant, an entire tree, and even a sofa.
- Borrowed Catchphrase: Gosalyn adapts her father's "I am the terror" catchphrase during her time as Yucky Duck.
- Brick Joke:
- Near the beginning, Gosalyn insists on joining Darkwing Duck and Launchpad on their latest crime-fighting caper and adds maybe grabbing a burger to eat as well. When she turns into a slime creature, she's brought along to assist Darkwing on his latest crime-fighting caper and stops by a Hamburger Hippo diner to eat some burgers (alongside fries, sandwiches, pies, sodas, cups, and paper plates).
- While following Gosalyn's trail to Bushroot's greenhouse, Darkwing accidentally crashes into a truck full of sheep. Later on, he uses said sheep to dispatch the living female lawn.
- Calling Your Nausea: Nonverbal example; Launchpad happily eats some fries covered in Gosalyn's slime, causing Darkwing to visibly gag.
- Enemy Mine: Bushroot and Darkwing team up to deal with the lawn woman brought to life by Bushroot's formula. Darkwing even lets Bushroot escape at the end, as his way of saying thank you.
- Forgot About His Powers: Bushroot misinterprets what Darkwing means by "grow up" at first until Darkwing repeats it.Bushroot: Oh, right, of course! Sometimes, I forget I'm part plant!
- Friendly Enemy: After their Enemy Mine situation, Bushroot becomes very interested in having Darkwing Duck become his friend! DW refuses to have it and has to forcefully push him into escaping.
- Gag Echo: At the beginning, Darkwing enters and says his catchphrase, only to find that everyone is gone. Launchpad suggests that he needs a shorter catchphrase. Gosalyn later adapts her father's catchphrase, only to find nobody is there. She muses that she needs a shorter catchphrase.
- Gone Horribly Right: Bushroot eventually succeeded in perfecting his IQ2U formula, but unfortunately, in the ensuing scuffle with Darkwing, the vial was buried by Spike, resulting in the lawn coming to life, with Darkwing and Bushroot having to work together to stop it.
- Hates Baths: Gosalyn struggles and gripes about being bathed at the end, whining that it's worse than being a slime monster, even though it was the only way to make her normal again (and prevent her from dying).
- Hidden Depths: Turns out that Gosalyn is fluent in Swahili; unfortunately, she ends up using it to beat Launchpad in a game with a wager on the loser being the winner's servant.
- Homework Slave: At the beginning of the episode, Gosalyn uses Launchpad as one. Drake isn't thrilled when he discovers this.
- Hypocrite: Drake tells Gosalyn that you're supposed to help friends, not use them. But that's exactly what he does when she becomes Yucky Duck - Darkwing began seeing her as a tool to catch criminals instead of a daughter. It takes Gosalyn running off and a mild What the Hell, Hero? from Launchpad to get him to his senses.
- I'm Melting!: Bushroot's initial IQ2U formula resulted in the plant subjects ultimately melting, and almost kills Gosalyn when she gets exposed to it. (She still hated the cure - plain soap and water.)Darkwing: I've taken a sample from Gosalyn, broken it down to its purest form, and tested it on plant subjects. Apparently, there are four stages. Intelligence... Indigestion... Insanity... and... In... a puddle.
- Literal Metaphor:
- During the encounter at the St. Canard Botanical Lab, Bushroot told Spike it was time for "a little tree action". By that, he meant small trees in pots attacking Darkwing and Launchpad.
- During the fight with the lawn, Darkwing told Bushroot "to grow up". Bushroot was initially hurt that Darkwing thought he was being childish, but he quickly realized he wanted him to extend upward over the lawn since he was part plant.
- Literal-Minded: Upon hearing that Bushroot broke into the St. Canard Nursery, Launchpad cried "Oh, those poor babies!". Darkwing Dope Slaps him, saying it wasn't that kind of nursery.
- Literally Shattered Lives: Darkwing and Launchpad try to use a ray to separate Gosalyn's slime molecules from her duck molecules. Unfortunately, it ends up separating her into several little blobs. Fortunately, she's able to reassemble, and even asks to do it again.
- Loophole Abuse: Darkwing grounds Gosalyn until she realizes that she needs to help and not manipulate her friends. Gosalyn quickly figures a way out of this by "reasoning" that if she should help her friends, she's officially no longer grounded, as she needs to go help her father and Launchpad catch Bushroot.
- Nobody Here but Us Statues: Bushroot and Spike try to hide from Darkwing by blending in with surrounding plants. Unfortunately, a tall flytrap like Spike still sticks out.Bushroot: (To Spike) Ooh, remind me to prune you when we get home!
- Slime Girl: Gosalyn is transformed into a slime creature. Initially, she looks like herself, albeit if she was covered in green goop. But over time her shape deteriorates; she gets fatter, loses her legs and starts oozing around instead, and eventually looks like this shapeless blob with only the barest hint of a beak and pigtails.
- What the Hell, Hero?:
- Seeing Gosalyn unscrupulously manipulate Launchpad into doing her homework and cleaning her room gets her a very stern lecture. And another grounding.
- Darkwing himself gets a mild one from Launchpad later for caring more about using Gosalyn's new slime powers to fight crime than about her well-being.
