"Sacred Cow" is the third episode in Season 1, being the third episode overall.
When a controversial documentary filmmaker places a live cow outside of the family restaurant to make a statement, Bob is livid when it starts to scare away customers. However, to everyone's surprise, Bob becomes attached to the cow and treats the cow like a member of the family.
Bob celebrates the restaurant's 100,000th burger and puts it on sale for half-price. A filmmaker named Randy starts filming his new documentary outside the restaurant, and ties a cow, named "Moolissa" (actually a male cow with a blonde wig on it) outside the restaurant. Bob sees this, and Randy explains his challenge for him: he can kill Moolissa and make her into a burger, or let her live; he is to make his decision when a timer placed outside the restaurant, called the "Cow-ntdown", stops. Louise begins calling Bob a murderer, attracting more attention to him. Putting Moolissa outside the restaurant backfires on Randy when it starts attracting customers for Bobs Burgers.
Later that night, Bob has a nightmare where he is in court, accused of killing Moolissa, and loses the case. He wakes up and sees it is raining outside and finds that Randy has left Moolissa tied-up outside in the rain. Feeling sorry for Moolissa Bob decides to let Moolissa into the house. While the children react positively to the idea, especially Gene and Tina in particular Linda demands that Bob to put her back outside. However, they fail to get Moolissa down the stairs, and as a result, Moolissa ends up staying inside with the Belchers. Randy finds Bob with the cow inside and reminds him he has got 2 days until the Cow-ntdown ends and to make his decision. The next morning, Linda reveals that she successfully let Moolissa out of the house (by putting her on a mattress with socks on), only to discover Moolissa missing.
Meanwhile, Tina sees some of Moolissa's feces and thinks it looks like a smiley face. Tina believes that Moolissa is trying to talk to her using her feces. Louise takes advantage of Tina and begins to make faces using a frosting bag. She makes a fake angry face and Tina begins wondering what she's done to bother Moolissa.
With Moolissa stolen, the Belcher family and the film crew team up to look for her, and discover that the cow was taken by a couple for their run down petting zoo, Mother Goose's Discount Petting Zoo. That night, they take her back, and get back to the restaurant in time for the timer to end and for Bob to make his decision. However, Bob says he wants more time, leading to an argument between him and Randy. As they argue, they fail to notice that Moolissa is walking across the road into the path of a moving van. The van's driver is able to hit the brakes right before Moolissa gets hit, but Moolissa dies shortly after of a "cow heart attack." Tina is saddened over his death but discovers his feces shaped into a heart. Bob faints after her death and enters his subconscious, where he is in heaven with Moolissa (voiced by Todd Barry). Moolissa tells Bob that he wants him to make a burger out of him, and they share a passionate kiss. The next day, Bob holds a funeral for Moolissa at the restaurant and decides to name his 100,000th burger the "Rest in Peas Burger" as the crew films it for the documentary.