It is the annual "Free Day" at the Bikini Bottom Zoo, and Mr. Krabs is helping himself to anything he can get his claws on. Meanwhile, SpongeBob and Patrick go to Oyster Stadium to see Clamu the giant oyster perform tricks. However, Clamu is sleeping, so Patrick quickly bails. SpongeBob tries to wake Clamu up by throwing a peanut at her, causing her to stir. SpongeBob calls Patrick back in anticipation for the show, which turns out to be a tragedy as Clamu thrashes around and attacks the zookeepers, crying inconsolably all the while.
After being questioned, SpongeBob and Patrick leave the park, SpongeBob feeling immensely ill at ease. Patrick decides to investigate the crime, determined to discover the culprit of Clamu's distress. At home, SpongeBob laments what he's done, but tells himself that the incident will soon blow over. However, when he turns on the TV, the oyster incident is the top news story. The Realistic Fish Head reports that Clamu's sobs are so powerful that they can be heard all around the world, and asks what kind of "cruel, careless, evil person" would do anything to upset the giant oyster.
With his guilt growing, SpongeBob goes to Squidward and Sandy for advice, but just like Patrick, both are concerned with finding and punishing the culprit, adding to SpongeBob's anxiety. To make matters worse, Patrick reveals that he found an incriminating bag of peanuts left near SpongeBob's home, stating that he's getting close to solving the mystery. Eventually, policemen enter SpongeBob's house and question him on the incident. SpongeBob admits to everything they ask him, but instead of arresting him, they conclude from their evidence that Patrick is the culprit, with Patrick having no choice but to agree.
Patrick is taken to Oyster Stadium, where he is chained to a platform in the middle of the stage and pelted with peanuts by the angry audience for the crime. Unwilling to let Patrick take the blame, SpongeBob arrives at the stadium and implores everyone to halt their assault. He finally confesses to having thrown the peanut, apologizing to Clamu, Patrick and the people of Bikini Bottom and asking for forgiveness. The audience, refusing to accept SpongeBob's apology, decide to throw peanuts at both him and Patrick, but before they can do so, a zookeeper arrives with Mr. Krabs in tow and stops them.
The zookeeper reveals that the true cause of Clamu's distress was the theft of her pearl, taken by Mr. Krabs while he slept. The zookeeper returns the pearl to Clamu. To everyone's surprise, the pearl turns out to be an egg, hatching into a baby oyster. Having been reunited with her offspring, Clamu finally calms herself down, emotionally touching the audience. This doesn't distract them from Mr. Krabs who, despite his protestation that it's Free Day, becomes the new target for their peanuts.
Clamu didn't cry instantly after the peanut has been thrown at her. The pause might be the time Mr. Krabs took the pearl.
Alternatively, the pearl could've been taken while Clamu was asleep, and she noticed it was missing after she was rudely awoken by the peanut.
The zookeepers who attempt to calm down Clamu was later seen in "Born Again Krabs," as paramedics.
The countries that are seen outside Bikini Bottom are Egypt, The Netherlands, and India, because of The Giza Pyramid, The Sphinx, and Taj Mahal.
The Realistic Fish Head mentions that other countries could hear Clamu's screaming, but if that was the case, then Bikini Bottom residents could have gotten deaf from it. It is possible the screaming is not that loud to the residents and they may hear it as regular loud screaming that could be heard from a distance.
The episode is a reference to a "smoking gun," a conclusive piece of evidence in a crime. The smoking gun, in this case, is the peanut.
The most notable "smoking gun" in American history is the piece of a phone conversation recording that mysteriously went missing in the Watergate scandal of the 1970s.
Clamu is a parody of the once popular and very famous whale Shamu in Seaworld.
When Clamu's loud wailing makes SpongeBob and Patrick fly to their seats, the peanuts in SpongeBob's bag flew out of the bag, but when Patrick said "Now this is a show!," his bag is full of peanuts again.
When SpongeBob knocks on Squidward's door, Patrick's house is nowhere to be seen.
Patrick's eyelids are usually purple. But when he says "Hey, SpongeBob!" when SpongeBob is trying to open his door, his eyelids are pink instead of purple.
When SpongeBob looked out his window, he saw Oyster Stadium. However, his house would have to be in the zoo to see Oyster Stadium clearly, as the stadium is inside the zoo.
When SpongeBob is about to go into his house after Patrick is saying he will investigate the lights are off but when he enters they are on.
This error happens again when SpongeBob says to Patrick "good luck with that."
It also happens when Patrick is arrested.
When the zookeeper pulls Mr. Krabs's pants off, his belt buckle colors are reversed to yellow on the inside and black on the outside, but in the next scene, the belt is back to normal.
At the end, some of SpongeBob's belt isn't completely filled in.