Kowalski invents an enemy detector, but when it malfunctions chaos breaks loose.
The episode begins as Burt is about to eat peanuts when a smoke bomb explodes. When the smoke clears Burt is shown tied to a tree with his trunk in a knot. Kowalski's Enemy Detector seems to have malfunctioned, and the same thing happens to multiple animals such as Mason and Phil, Shelly, Leonard and even Barry. Eventually Skipper gets fed up with the continuous malfunctions that he hits it, only to be electrocuted. Skipper wakes up seeing his friends as enemies and thus attacks the others. Kowalski then realizes his mistake- he had the circuit board upside down. Skipper heads to Hoboken where he sees Hans as his friend, and thus returns to the Central Park Zoo where the penguins are having a meeting with the other animals based on the crisis. Skipper and Hans ambush them. During the night, Skipper encounters Julien while Hans is away, and sees him as a friend. The penguins then pull Julien into the popcorn cart and Kowalski explains what is going on. (Which also means that Skipper did not like Julien, as opposed to what Dr. Blowhole said in Dr. Blowhole's Revenge). Later, Hans and Skipper are eating ice cream when Hans decides to get a salmon. Julien then distracts Skipper, but as he wants to stay a friend to Skipper changes his mind and blows the penguins' cover. The penguins are then seen locked in a cage similar to the one in All Tied Up With a Boa. Skipper then decides to have the zoo full of his "friends" only, such as the Sewer Rats, Savio and Officer X. Skipper and Julien do Conga dancing together, when Hans returns. Hans and Julien fish fight (though Julien's weapon is Mort) for Skipper's friendship until Julien decides to split Skipper in half and takes the hacksaw Rico had regurgitated to escape the cage. Skipper is knocked out cold into the cage and Kowalski immediately fixes Skipper's mechanic error. Skipper cheers Julien up, which makes Julien decide to throw the Enemy Detector at him. Unfortunately, Mort is electrocuted and sees Julien's feet as his enemy, thus chases him with a mace.