The man who visits all the homes in South Park every day is now under suspicion. The luxury of having packages delivered to your doorstep is suddenly a threat to every family in the neighborhood.
Cartman takes matters into his own hands and signs up for a home security system.
Gerald and Sheila role play in the bedroom, with Gerald dressed as a UPS man after he watches a Cialis commercial. Without them knowing and with the door open, Ike sees them and ends up crying for most of the next day, not realizing the UPS man was in fact Gerald. Kyle asks what is wrong, and Ike draws a stick figure picture of a UPS man having sex with Sheila.
Kyle confides in Stan, Kenny and Cartman, who advise him to confront Sheila about it. Randy overhears the conversation and tells the other males of South Park. After listening to a story from a shady old man in Skeeter's Bar and Cocktails, who compares it to a milkman who used to have sex with people's wives while doing deliveries and calling it "the price to pay for convenience", they all grow paranoid of the UPS delivery men having affairs with all their wives, and begin spying on the delivery men. Randy notes that Sharon could not remember what her Amazon package contained upon its delivery, and signs for it himself to avoid contact between the one UPS man, called Thad, and Sharon.
People start buying excessive home security measures, that Cartman in particular finds frustrating because the man who rings up upon an alarm sounding is useless, so he tests it by hiring a burglar to break in and rape his mother. By the time any appreciable response was achieved, it was far too late.
Despite the extra security, the paranoia grows and the men consult the shady bar patron again, who advises them to "kill the milkman". Donning Bane masks, they drive the UPS Man to a secure storage facility and severely beat him. This causes further security concerns, due to the presence of seven Banes as opposed to one. Everyone buys an improved security system, "InSecurity", that detects fear levels and goes off if they get too high. Upon Cartman flouting this to Kyle, who he is convinced is repeatedly robbing his house, he accidentally sets his InSecurity alarm off upon Kyle shooting down one of Cartman's jabs at his religion by telling him Jewish populations are growing.
The UPS man, on return from hospital, continues his deliveries, eventually resulting in his van being blown up by Stephen while Kyle attempts to get his mother to confess to having an affair. The UPS Man then commits suicide, due to being so scared, by jumping out a window to his death. Upon investigation of the house, the police, called by the UPS man's InSecurity alarm, find Gerald's UPS uniform, and Gerald hurriedly explains that he desperately needed to spice his sex life up. This sets off everybody's InSecurity alarms.
Cartman, fed up with the false alarms and poor service, approaches the home security man while wearing a Bane mask and holding a gun, warning him he should have respected his "authoritah".
AV Club gave "Insecurity" a "B" rating saying: "Insecurity did its best to link up the fear of cuckoldry with the fear of home invasion, but the results themselves were mixed. Still, they worked enough to make the episode on the whole fun, if not as strong as the first two outings this fall. Having each man’s respective Insecurity alarms go off simultaneously at the mere mention of erectile dysfunction drugs tied everything back to its inauspicious beginnings. But the connective tissue between those two moments was frayed enough to keep it out of this season’s top-tier episodes."
IGN gave "Insecurity" a "8.3" rating saying: "Indeed, the home security jabs along with the Bane impersonations were a nice combination this week. While the plot here was clearly framed around recycling these two jokes over and over, they were both strong enough to carry out the 22 minutes in full. The additional "ordering stuff from Amazon and not remembering" thing wasn't quite as sharp, but given the ridiculous circumstances, it did the job. Overall, "Insecurity" was yet another admirable entry for Season 16."