Robin's musical past emerges again as the group learns of someone named Simon from Robin's past. Barney searches for more Robin Sparkles memorabilia.
Nathan and Haley have learned from the mistakes with the nanny, so they decide to interview potential nannies or mannies, but it goes in a completely different way. Meanwhile Brooke still wants to go ahead with adopting a baby. Mouth and Millicent take a new step in their relationship and Quentin must reconsider his intentions.
Having been recently dethroned as Queen Bee, Blair returns to school with the support of Serena to find she is still on the outs with her old friends. Dan visits his mother over spring break, and when he returns, Jenny is on the verge of becoming a full-fledged member of the A-List crowd. Jenny must go to dangerous and even illegal lengths to fit in. Serena struggles to adjust to living with Chuck, and receives disturbing packages from an unknown sender.
Alan feels Charlie is unable to control his womanizing ways.
In the final 30 minutes before Brent turns 40, Wanda tries to pull off a fireworks display for the occasion that goes terribly wrong. Lacey and Emma disagree over just who should be baking Brent's birthday cake, and Brent is dismayed to discover that his special bottle of scotch has gone missing.
George and The Man With the Yellow Hat travel on a boat with Professor Wiseman as well as Professor Pizza and Professor Einstein to retrieve a weather satellite that has fallen from space into the ocean. The only problem is that the satellite has fallen into the middle of a coral reef which is very brittle, so George dives down to retrieve it himself.
Mia finally joins the spirit squad and finds her past is back to haunt her. Meanwhile Manny wants to meet Jay's parents.
Continuing in Japan, Scott and Justin seek the peace of nature by taking a late-night ferry to the island of Miyajima and try to find camp amongst the hundreds of native deer and discover that they may have taken for granted their decisions and ability to travel the world.
Adam wants Russell to agree to hire Jen to design an ad campaign for one of their clients. He will not listen to Russell and Jeff when they tell him that this is not a good idea. When Audrey shares the fertility issues with Jen, she gives them a gift to help bring them luck.
Mike travels to Alaska for an adventure aboard a fish processing ship.
Samantha finds out about an endangered butterfly habitat and needs to stop her boss and the firm's construction project that would kill them. She decides to use Dena, who is clueless about Sam's plan, to go out with her boss and persuade him to stop the construction project. After Todd and Sam's passionate kiss, Sam is feeling ignored by him.
Allison has visions of a friend of Scanlon and Lynn DiNovi dying in a home mishap. This causes her to struggle with connecting some recent "accidental" deaths, consequently putting her own health in jeopardy.
Lauren and Lo are looking into the real estate market as they plan to buy a house. Meanwhile, Audrina reconsiders her situation as a single woman.
It's Earth Day in Bed Stuy and Chris decides to collect cans because he believes it will be easy and that he can get Julius to help. Meanwhile, Rochelle is called into Tonya's school for inappropriate behavior and realizes just where Tonya's attitude comes from.
May 1945. Foyle joins a municipal committee that's preparing for the now imminent V-E Day celebration but soon finds himself investigating the deaths of two of its members.
Wyatt has a fear that Marlowe could break up with him after they've gotten on each other's nerves for a while. Caitlin meets a cute boy named Calum at a party and later realizes he's a nerd so she writes him a fake phone number, but she writes the number on the back of her very own Khaki Card, on which she saved shopper's card points since she was 14 years old. So Caitlin needs to find a way to search for Calum and get her Khaki card back.
Three teenagers from the Pai Zhug Kung Fu Academy are chosen to fight the forces of an opposing academy and all other forces of evil.