Tick-Tick-Tick is the fourth episode of Kim Possible, though it is actually the first episode chronologically.
While trying to print her term paper in time for class, Kim Possible lands herself in detention for being tardy for the third time that month (courtesy of Mr. Barkin). For Kim, this is a huge deal due to her status as a cheerleader and how it makes her look; however those worries are put on hold after Wade informs her of an incident in the Amazon. He hooks her up with a ride with Gustavo whose village Kim saved from a flood of the Amazon. A bug researcher name Professor Acari has had his experimental robotic tick stolen by an unknown thief for an unknown purpose. Ron is completely freaked out by all of the professor's bug friends. It is later revealed that the thief was Shego and that she is working under the employment of Dr. Drakken. Back in Middleton, Kim serves her first block of detention in Room 12 with Big Mike, Vinnie, and Junior, all of whom are not of the same caliber. Detention is thankfully cut short by Rufus who poses as a rampaging mutant who had broken free from the science lab. At Bueno Nacho, Kim is given an update by Wade about a villain's lair in the Caribbean that is linked back to Shego. Team Possible heads to the Caribbean lair but are immediately captured by Dr. Drakken and almost fed to man-eating sharks but Kim manages to apprehend them with her Elastic Constricting Agent disguised as lipstick. Drakken plans to combine the robotic tick with his own nano-explosive as a threat weapon. Once attached to a victim, they will be at his mercy. Despite Drakken's plan, Kim is able to retrieve the plans for the robotic tick and flee Drakken's lair.
Upon returning to Middleton High, Ron is jealous of Kim's new "street cred." Mr. Barkin puts Kim back into detention after identifying the mutant as a naked mole rat. Meanwhile back in the Caribbean, Drakken and Shego discover that the missing tick is with Kim Possible. In detention, the other teens noticed a "zit" on Kim's nose that turns out to be the robotic tick. Immediately Kim ditches detention to find Ron and try to get the tick removed before it explodes. Unfortunately for her, Drakken as well as Mr. Barkin (with the teens in tow) engage in hot pursuit of Kim and Ron. After seeking refuge in Bueno Nacho, Kim and Shego fight while Wade tells Ron that the only way to remove the tick is to burn the circuits. Ron immediately thinks of Diablo Hot Sauce. They are interrupted by Shego for a moment but she is sat on by Big Mike. Ron uses the hot sauce to remove the tick which explodes immediately after Kim throws it towards Drakken's hovercraft. Even though Drakken is thwarted, Kim still serves her detention but this time making friends with the people she had previously deemed not cool (countering Barkin's objective of making detention a period of quiet suffering).