A voice, not unlike God’s, describes a deadly threat to humanity’s existence that has surfaced in the most unlikely of places. Crystal, Ronnette, and Chiffon come on and introduce…the Little Shop of Horrors. They warn the audience to beware of the dangers that lie ahead (“Little Shop of Horrors”).
We are in Mushnik’s Skid Row Florists shop. Hours slowly tic by on a clock. At 10 a.m. an earsplitting crash echoes from the back room. Seymour assures Mushnik, who is reading the paper, that nothing is broken. At 11;00, Audrey, Mushnik’s dizzy blonde employee, comes in with a black eye. Even though he has had no customers all day, Mushnik scolds her tardiness as another crash erupts from the back room. Noticing Audrey’s black eye, Mushnik suggests that her boyfriend is not a nice boy. Audrey reminds Mushnik that you don’t meet nice boys on skid row. Seymour comes out and proceeds to dump a tray of re-potted plants. Mushnik yells at him, but Audrey intervenes. Fed up with everything, Mushnik chases Ronnette, Crystal and Chiffon off of his stoop. Things are rough for everyone in Skid Row, but Seymour has a dream to get out (“Downtown [Skid Row]”).
At six o’clock, without having had a single customer, Mushnik announces that he is closing the flower shop for good. Seymour suggests that the shop should move in a new direction. He has been working on a strange and interesting plant, which he has named Audrey Two. Seymour says they could display Audrey Two in the window to attract customers. Mushnik scoffs, but a customer shows up and asks about the strange and interesting plant in the window. As the urchins back him up, Seymour describes how he bought the plant from an old Chinese man during a total eclipse of the sun (“Da-Doo”). Fascinated by the story, the Customer decides to buy one hundred dollars worth of roses. After the Customer leaves, Mushnik puts Audrey Two in the window and offers to take Seymour and Audrey out to dinner. Audrey declines because she has a date with her professional rebel boyfriend. Instead of dinner, Mushnik orders Seymour to stay with Audrey Two who looks unhealthy. Left alone with the plant, Seymour does not know what it needs – he’s tried feeding it everything, but it’s still sickly (“Grow For Me”). When Seymour accidentally pricks his finger on a rose, he realizes what Audrey Two is hungry for: blood.
Some time later, a radio show interviews Seymour proclaiming him a botanical genius for inventing a new kind of plant. Seymour reminds the listeners that Audrey Two is on display at Mushnik’s Skid Row Florists. Although he is unhappy that Seymour did not give the shop’s address, Mushnik is thrilled by his newfound success. Chiffon, Ronnette, and Crystal great Seymour upon his return and celebrate his success; meanwhile, Audrey Two is snapping at the humans (“Ya Never Know”). Audrey rushes on and apologizes to Seymour for missing the broadcast; she was handcuffed to her boyfriend. Ronnette, Chiffon, and Crystal suggest Audrey get a new man – Audrey doesn’t think Seymour would want her. Still, she dreams of the life that she and Seymour could have in the suburbs (“Somewhere That’s Green”).
A week later, the flower shop is undergoing a major renovation. Because Audrey Two has been attracting a lot of customers, Mushnik, Seymour and Audrey are making much needed improvements to the store (“Closed for Renovation”). Audrey Two is now five feet tall with spiked leaves. Mushnik asks Seymour about a very important funeral account. When Seymour admits that he’s forgotten about it, Mushnik yells at him and storms off. Audrey tells Seymour that she thinks Mushnik’s too hard on him. Seymour feels he owes Mushnik for getting him out of the Skid Row Home for Boys when he was a child. Audrey thinks Seymour should raise his expectations and offers to take him shopping for new clothes. Surprised that Audrey wants to be seen in public with him, Seymour asks if she’s free that night. Unfortunately, Audrey has a date.
Meanwhile, on the street, Orin Scrivello, in a black leather jacket, asks Crystal, Ronnette, and Chiffon where the flower shop is so he can pick up his date. Realizing that Orin gave Audrey her black eye, the girls descend on Orin and beat him up. Orin offers a truce and explains that he is not a monster. He explains his work requires a fascination with pain and suffering; he is a dentist and describes his life’s calling to cause pain and misery (“Dentist!”).
In the Florists, Orin is amazed by Audrey Two. He tells Seymour that he shouldn’t stay on skid row because the plant is a ticket to something better. Audrey tries to explain that Seymour is loyal, but Orin ignores her. Seymour says he’ll think about leaving like Orin said. Orin and Audrey leave. Mushnik has overheard this and he worries that Seymour will leave, and take Audrey Two. To get him to stay, Mushnik offers to adopt Seymour as his son (“Mushnik and Son”). Mushnik rushes off. Now happy that his luck has changed, but feeling dizzy from feeding Audrey Two so much of his own blood, Seymour starts to go to get some dinner. The plant wilts, but Seymour assures it that he will feed it in a few days. Suddenly the plant speaks. It demands to be fed. Seymour says he has no more blood left. The plant promises Seymour fame and success in exchange for more blood. Seymour has strong reservations about killing people, but the plant reminds Seymour that a lot of people deserve to die. At that very moment, Orin and Audrey return. Audrey has forgotten her sweater, and Orin slaps her around for it. Seymour and the plant reach the same conclusion about the plant food (“Git It”).
Later, Seymour finds Orin at his office and points a gun at him. Orin easily takes the gun from Seymour, wrestles him into the dentist’s chair, and threatens him with the drill. Orin then pulls out a container of laughing gas, complete with a gas mask and puts it on himself to get high. In a gassed-out blissful moment, Orin disappears behind the chair. Seymour realizes that he should kill Orin now while he has the opportunity, but he cannot bring himself to pull the trigger. Meanwhile, Orin cannot get his gas mask off and realizes that he could asphyxiate to death. After much internal ethical debate, Seymour decides not to remove Orin’s gas mask. Consequently, Orin laughs himself to death (“Now [It’s Just The Gas]”).
The sign in the flower shop window now reads ‘Mushnik and Son.’ The store is bustling with phone calls and customers. Late for a meeting with his lawyer, Mushnik runs out as Seymour runs in after making another delivery. Audrey and Seymour handle a deluge of phone calls from customers (“Call Back In The Morning”). When the clock hits six, Audrey and Seymour are exhausted. Seymour tells Audrey that he’s been shopping for a new wardrobe and shows off his new black leather jacket to her. Audrey is overcome with emotion. Seymour, taking off the jacket, tells her that he just wanted to impress her. Audrey admits that she feels guilty for being glad that Orin is missing, and she secretly hopes he had a terrible accident. Seymour tells her that she deserves a nice guy, but Audrey disagrees: she dances at a tasteless nightclub for extra money. Seymour sees the girl underneath the makeup and he vows to be her friend (“Suddenly Seymour”). Seymour and Audrey embrace passionately. Mushnik walks in on them. Staring at Seymour, Mushnik ominously asks Audrey if she’d like to visit her dentist friend. Seymour reminds Mushnik that Orin disappeared and sends Audrey home. When Audrey is gone, Mushnik notices little red dots on the floor. Seymour insists he spilled punch. Mushnik then informs Seymour that he was called to the police station because a Mushnik shopping bag was found in Orin’s office. Mushnik charges over to the trash and pulls out a dentist’s outfit; he accuses Seymour of killing the dentist in order to get his girl. Seymour maintains his innocence until Mushnik shows him a picture of his baseball cap that was found in Orin’s office. Twoey starts to subconsciously urge Seymour to feed him, contending that Seymour will lose everything if Mushnik takes him to the police (“Suppertime”). Seymour tricks Mushnik into going inside the plant, which immediately eats him.
Distraught and disturbed, Seymour leaves the flower shop. Ronnette, Chiffon, and Crystal accost him like squealing teenage fans. They tell Seymour that another Uptown big shot is looking for him. Offers are coming in fast and furious from news programs, agents, and speaking tours. Realizing that his success will come with more killing, Seymour has secretly decided to kill the plant. However, he realizes Audrey might not like him without the success the plant has helped him win. Determined to keep Audrey, Seymour reneges on his decision and takes the offers as the girls remind him that the meek get what’s coming to them (“The Meek Shall Inherit”).
Patrick Martin from World Botanical Enterprises enters, finding Seymour shattered by Audrey’s demise. Martin wants to take leaf cutting from Audrey Two and sell them to every florist in America. Pretty soon, every household in America will have its own Audrey II. Martin goes back to his truck to get some flowerpots. Seymour realizes that the plant has been planning world conquest all along. The plant tells Seymour that it is too late to stop it. Seymour pulls out a gun and shoots the plant. The plant laughs. Seymour forces the plant to eat rat poison. The plant just spits it out. Seymour grabs a machete and climbs into the plant, intending to hack it up from the inside. The plant closes in on him and spits out the machete.