Andre encounters a Neuro from his past that was chipped, but he learns that she has regained her abilities and she has a grudge.
Lucy persuades Lee to pretend to be gay after she lies to a business acquaintance Guy, who she was told is gay himself, by telling him she lives with a gay flatmate to prove she is not homophobic. However, Guy soon starts to get suspicious and tests Lee's sexuality by taking him to a gay bar. Later, Guy overhears Lee saying to Tim, who had started to think Lee was gay, that he is not gay. When Lucy then explains to Guy what happened, he reveals he is not gay and he and Lucy kiss.
Eric Nishijima is using a particle accelerator to wipe out the contractors. Amber gathers numerous contractors to destroy the accelerator, and dolls to be used for some other unknown reason. Nijishima is related to the Syndicate as he places a phone call to eliminate Hei and his team. Amber sends a message to Hei via Wei, telling him to meet her in the Gate. Hei agrees and thus Huang, Mao, and Yin, agree to assist Hei to infiltrate Hell's Gate with Wei's guidance.
Big Bird and Elmo are excited, because they've got a special song for two friends, which they are. They count each other, and sing "One and One Make Two." They almost sing it again, when Abby Cadabby appears in a poof, and asks to join them. Suddenly, Big Bird realizes the song won't work this time, because it's a song for two, and if Abby joins them, they won't be two anymore, but three. What to do? Abby suggests making herself disappear, but that turns out to be not such a good idea. The three friends decide they should ask Gabi what they should do. They explain their predicament, and Gabi suggests they sing a song for three instead of two. What a great idea!
Princess Pea and Red are paired up in a potato sack race. The only problem is that they can't decide on what speed they want to go. The Super Readers travel into the Tortoise and The Hare book. They discuss the book and learns about winning isn't always about coming in first.
Michael is hired to track down a woman's estranged husband, who has disappeared with their son. Michael soon finds himself pitted against somebody just as skilled and dangerous as he is.
A rival ad agency courts Don, involving Betty in their attempt to lure him from Sterling Cooper. As the presidential campaign heats up, the agency looks for new ways to counter the latest Kennedy ads. Tempers flare over Peggy.
Jonesy, Wyatt, and Jude agree not to shower or clean themselves for a week to determine which one of them smells the worst and the best, with Nikki, Jen, and Caitlin as the judges. Meanwhile, Caitlin persuades her new boyfriend to try and get a good baby picture in a brand new "Make A Baby" booth that's just been added to the mall, but every picture she takes with him ends up ugly. When Jen goes in with Jude, their baby is perfect, which makes Caitlin break up with her boyfriend and look around the mall for cute boys she can go in with to have a perfect baby.
The evil and accent challenged Prime-Minister of Slovenia plans to kill the country’s Princess in order to take control. For his coup to work, he must first hire bodyguards for her to divert suspicion away from him, and secondly make sure the bodyguards are an incompetent bunch of numb nuts. No second-guessing who gets the job.
Bloo feels torn between Mac and a new student, who is the heir to a paddleball franchise.
Continuing on their way to Hearthome City, Ash and his friends take a side trip to get an upgrade for Dawn's Poketch. Unfortunately, they ended up getting trapped in a dangerous maze, courtesy of Team Rocket.
Dennis joins up with an environmentalist group, but his altruistic intentions quickly sour when he's snubbed by the activists. Dee and Mac decide to raise a baby they find in the dumpster, but quickly find out that it's not nearly as fun as they thought it would be, and Frank and Charlie take the concept of recycling a bit too far.
Mac, Dennis and Dee try out for the Philadelphia Eagles. Also interested in becoming an Eagle is Liam and Ryan McPoyle's brother, Doyle.
With Blaine as Clover's official boyfriend, Clover's love life is perfect. She was even convinced he was "the one." Although her love life is awesome, her spy life isn't running so smoothly. In fact, after a mission at The Groove back in Beverly Hills, where Clover gets attacked by a mysterious person, he accidentally leaves behind a small air pump for volleyballs. The pump has Mali-U's logo on it and each member of the Mali-U beach volleyball team has one - even Blaine! Will the spies find out what Blaine is really up to? In a b-story, Clover dreams about her future plans with Blaine.
At the Fix-it Shop, Abby Cadabby and Elmo watch Maria fix a toaster. ("I love having an audience," Maria says.) An excited Rosita rushes over to show them the letter she received from her abuelita, and asks Maria to read it. In the letter, her grandma says she was looking at a picture of Rosita, and it made her happy. It makes Rosita happy, too, as she imagines a hug from her abuelita. Right then and there, Rosita decides to write a letter back, and runs off.
In the fourth-season finale, Sheila learns that Jimmy's ghost has been spotted on several occasions, so she investigates. Meanwhile, Colleen blames Tommy for her failed relationship; Franco and Natalie come to an understanding, as do Lou, Cousin Mike and Latrina; and Tommy spends time with his father.
Bloo wants to grow up because he thinks Mac is engaged.
Mr G takes over the drama department and causes chaos, Ja'mie has her first day at school Jonah tries to fix his bad ways.