In a small rural Pennsylvania town in July 1957, teenager Steve Andrews (Steve McQueen) and his girlfriend, Jane Martin (Aneta Corsaut), are kissing at a lovers' lane when they see a meteorite crash beyond the next hill; Steve decides to look for it. An old man (Olin Howland) living nearby finds it first. When he pokes the meteorite with a stick, it breaks open, and a small jelly-like globule inside attaches itself to his hand. In pain and unable to scrape or shake it loose, the old man runs onto the road, where he is nearly struck by Steve's car; Steve and Jane take him to Doctor Hallen (Stephen Chase).
Doctor Hallen anesthetizes the man and sends Steve and Jane back to locate the impact site and gather information. Hallen decides he must amputate the man's arm since it is being consumed. Before he can, The Blob completely consumes the old man, then Hallen's nurse, and finally the doctor himself, all the while continuing to grow. Steve and Jane return in time for Steve to witness the doctor trying to get out the window with the creature on his head. They leave and go to the police station and return with Lieutenant Dave (Earl Rowe) and Sergeant Bert (John Benson). There is no sign, however, of The Blob or its victims, and Bert dismisses Steve's story as a teenage prank. Steve and Jane are taken home by their parents, but they later sneak out.
In the meantime, the creature consumes a mechanic at a repair shop and grows in size every time it consumes something. At the Colonial Theater, which is showing a midnight screening of Daughter of Horror, Steve recruits Tony (Robert Fields) and some of his friends to warn people about The Blob. When Steve notices that his father's grocery store is unlocked, he and Jane go inside. The janitor is nowhere to be seen. Then the couple are cornered by the creature; they seek refuge in the walk-in freezer. The Blob oozes in under the door, but quickly retreats. Steve and Jane gather their friends and set off the town's fire and air-raid alarms. The townspeople and police still refuse to believe Steve. Meanwhile, the creature enters the Colonial Theater and engulfs and devours the projectionist before oozing into the auditorium, consuming a number of the audience. Steve is finally vindicated when screaming people leave the theater in blind panic.
Jane, Danny, and Steve become trapped in the diner, along with the manager and a waitress. The Blob, now enormous and blood red from the people it has consumed, has engulfed the building. Dave has a connection made from his police radio to the diner's telephone, telling those in the diner to get into the cellar before they bring down a live power line onto the diner.
When the live wire lands, it discharges a massive electrical current into The Blob, but it is unaffected and the diner is set ablaze. When the diner manager uses a carbon dioxide extinguisher on the fire, Steve notices that this causes the creature to recoil. Steve remembers that it also retreated from the freezer, saying "That's why it didn't come in the ice box after us. It can't stand cold"! Shouting in hopes of being picked up on the open phone line, Steve tells Dave about The Blob's vulnerability to cold. Jane's father, Mr. Martin (Elbert Smith), leads Steve's friends to the high school to retrieve the twenty fire extinguishers there. Returning, the brigade of fire extinguisher-armed students and police first drive the creature away from the diner, then freeze it, saving Steve, Jane, and the others.
Dave requests authorities send an Air Force heavy-lift cargo aircraft to transport the Blob to the Arctic, where it is later parachuted down to the ice and snow pack. Dave says that while the creature is not dead, at least it has been stopped. To this, Steve Andrews replies, "Yeah, as long as the Arctic stays cold".
When The Blob first premiered as the B film of the double bill with I Married a Monster from Outer Space, it was quickly moved up to be the main feature. While audiences liked it, critics were not as kind. The review in The New York Times highlighted some of the problems and identified some positives, although Steve McQueen's debut was not one of them. Concentrating on director Irvin Yeaworth's work, "Unfortunately, his picture talks itself to death, even with the blob nibbling away at everybody in sight. And most of his trick effects, under the direction of Irvin S. Yeaworth Jr., look pretty phony".[8]
The review continued with, "On the credit side, the camera very snugly frames the small town background — a store, a church spire, several homes and a theatre. The color is quite good (the blob rolls around in at least a dozen horrible-looking flavors, including raspberry). The acting is pretty terrible itself, there is not a single becomingly familiar face in the cast, headed by young Steven McQueen and Aneta Corseaut."[8]
Variety had a similar reaction, seeing McQueen as the star, gamely "giving the old college try" but that the "... Star performers, however, are the camerawork of Thomas Spalding and Barton Sloane’s special effects".[9]
In a discussion with biologist Richard Dawkins, astrophysicist Neil deGrasse Tyson stated that among all Hollywood aliens, which were usually disappointing from a scientific perspective, The Blob was his favorite.[10]
The review aggregator website Rotten Tomatoes reported a 68% approval rating based on 31 reviews, with an average rating of 6.3/10. The website's critical consensus reads, "In spite of its chortle-worthy premise and dated special effects, The Blob remains a prime example of how satisfying cheesy B-movie monster thrills can be."[11]
In May 2018, the film was shown on the very popular, Chicago based “Svengoolie” Show on “MeTV” and while host Svengoolie was giving background info on the film, he explained that this film was the last time McQueen was ever listed as Steven on film credits. McQueen would go on star in “Wanted: Dead Or Alive” which reruns also currently air on “MeTV”
Since 2000, the town of Phoenixville, Pennsylvania, one of the filming locations, has held an annual "Blobfest". Activities include a re-enactment of the scene in which moviegoers run screaming from the town's Colonial Theatre, which has recently been restored.[18] Chef's Diner in Downingtown is also restored, and is open for business for photographs of the basement on weekday mornings only.
The Blob itself was made from silicone, with increasing amounts of red vegetable dye added as it "absorbed" people. In 1965, it was bought by film collector Wes Shank,[19] who has written a book about the making of The Blob.[20]
According to Jeff Sharlet in his book The Family, The Blob was "about the creeping horrors of communism" only defeated "by freezing it — the Cold War writ small and literal".[21] Rudy Nelson, one of the scriptwriters for the film, has denied many of Sharlet's assertions, saying "What on earth can Sharlet say about the movie that will fill 23 pages—especially when what he thinks he knows is all wrong"?[22]
In 1997, film historians Kim R. Holston and Tom Winchester noted that the film was "Filmed in southeastern Pennsylvania at Valley Forge Studios, (and) this very famous piece of pop culture is a model of a decent movie on a small budget".[23]
The poster for The Blob was briefly shown in Steven Spielberg's 2017 film The Post starring Tom Hanks and Meryl Streep.
The film is recognized by American Film Institute in these lists:
2001: AFI's 100 Years...100 Thrills – Nominated[24]
2003: AFI's 100 Years...100 Heroes & Villains:
“The Blob” – Nominated Villain[25]