Curt Siodmak wrote The Ape a full year before he’d write The Wolf Man (1941) — the screenplay that would make his name synonymous with classic horror for the rest of film history. The Ape is what he was doing beforehand, on assignment for Monogram Pictures, the cut-rate studio that couldn’t afford Universal’s monsters and instead built a horror slate around whatever Boris Karloff was contractually obligated to appear in that year. This was the sixth and final film of that contract, and it shows every sign of what one retrospective called a “contractual obligation album” — Karloff giving the material his customary professionalism regardless of what he’d been handed.
What he’d been handed is genuinely strange even by 1940 mad-scientist standards: a kindly small-town doctor secretly murdering people to harvest spinal fluid for a polio cure, at the exact same moment an escaped circus ape is loose and mauling locals nearby. The film’s real twist — that Karloff’s Dr. Adrian eventually disguises himself using the actual skinned hide of the dead ape to commit his own murders — is stranger than anything the film’s flea-bitten monster suit budget would suggest it’s capable of. It’s a genuinely odd little picture, and it’s in the public domain, free to watch right now.
The Ape 1940 — Movie Overview Table
| Detail | Information |
|---|---|
| Title | The Ape |
| Release Year | 1940 (released September 30, 1940) |
| Country | United States |
| Runtime | 62 minutes |
| Genre | Horror, Mad Scientist, Monster Film |
| Language | English |
| Format | Black & White |
| Director | William Nigh |
| Screenplay | Richard Carroll and Curt Siodmak (credited as “Kurt Siodmak”) |
| Based On | The Ape, a play by Adam Hull Shirk |
| Earlier Adaptation | The House of Mystery (1934), also directed by William Nigh |
| Cinematography | Harry Neumann |
| Film Editing | Russell F. Schoengarth |
| Music | Edward J. Kay |
| Makeup | Gordon Bau |
| Producer | Scott R. Dunlap (William T. Lackey, associate producer) |
| Production Company | Monogram Pictures Corporation |
| Notable Uncredited Role | Ray “Crash” Corrigan as the ape |
| Significance | Final film of Boris Karloff’s six-picture Monogram contract |
| IMDb Rating | 4.6/10 |
| Public Domain | Yes — freely available to watch and download |
Full Cast Table — The Ape (1940)
| Actor | Role |
|---|---|
| Boris Karloff | Dr. Bernard Adrian |
| Maris Wrixon | Miss Frances Clifford |
| Gene O’Donnell | Danny Foster |
| Dorothy Vaughan | Mother Clifford |
| Gertrude W. Hoffmann | Jane, Adrian’s Housekeeper |
| Henry Hall | Sheriff Jeff Halliday |
| Selmer Jackson | Dr. McNulty |
| Ray “Crash” Corrigan | The Ape (uncredited) |
Curt Siodmak — One Year Before The Wolf Man
What makes The Ape worth a second look, beyond Karloff, is the screenwriter attached to it. Curt Siodmak — billed here as “Kurt Siodmak” — co-wrote the picture with Richard Carroll during a stretch of his career spent bouncing between low-budget assignments like this and Universal’s Invisible Man sequels, still a year away from writing The Wolf Man (1941), the script that would cement his reputation as one of horror’s defining screenwriters.
One retrospective review credits Siodmak, alongside Carroll, with being among the first horror screenwriters — if not the very first — to use spinal fluid specifically as the story’s central plot device. Even critics unimpressed by the finished film tend to carve out an exception for the writing’s underlying ambition: an IMDb reviewer conceded the film was “better than I expected, thanks not only to Karloff’s sympathetic performance but to a script by Curt Siodmak, who did much better things” elsewhere in his career. It’s a film best understood as an early, imperfect dry run for ideas Siodmak would refine considerably better within twelve months.
Boris Karloff at Monogram — The End of a Six-Picture Contract
The Ape closed out a run that had kept Karloff busy at the notoriously cut-price Monogram since 1938, most of it spent playing the detective Mr. Wong across five prior pictures directed by the same William Nigh — a series that required Karloff to perform in “yellowface,” a now widely criticized casting convention typical of the era’s mystery genre. Nigh had, decades earlier, directed Lon Chaney as well, giving him the unusual distinction of having worked with two of Universal-adjacent horror’s defining stars across two different eras — a fact one reviewer noted made The Ape‘s pairing something like a spiritual bookend to Nigh’s own career path.
Despite the thin material, reviewers across decades consistently single out Karloff’s performance as the reason to watch at all. Rotten Tomatoes’ aggregated critical view describes the film as “largely unworthy of its star,” even while conceding Karloff remains its prime draw, and other assessments have praised what one called a “delightfully touching, hammy performance” that elevates otherwise silly material considerably above where the script alone would leave it.
Full Plot Summary — The Ape (1940)
Dr. Bernard Adrian (Boris Karloff) is a kindly, respected physician in a small town, viewed with a mixture of suspicion and reverence by the locals. He lost his own wife and daughter to paralysis — the film’s careful euphemism, under the era’s Hays Code restrictions, for what is clearly polio — and has devoted himself since to developing a serum capable of curing the disease in others, particularly Frances Clifford (Maris Wrixon), a young wheelchair-bound woman he’s grown deeply attached to.
The Escaped Circus Ape
Running parallel to Adrian’s research is a second plot thread: a vicious ape has escaped from a local traveling circus and is loose in the countryside, terrorizing residents. Sheriff Jeff Halliday (Henry Hall) is left trying to track the animal down and solve a string of mysterious killings that begin cropping up around town — killings that, unbeknownst to him, aren’t entirely the ape’s doing.
Adrian’s cure requires a steady supply of human spinal fluid, and he’s running perilously low. As his desperation grows, he begins killing local townspeople to extract what he needs — and, in the film’s most infamous plot turn, disguises himself using the freshly killed ape’s own hide to commit at least some of these murders, letting the sheriff and the town believe the escaped circus animal is responsible for crimes that are, in fact, Adrian’s own doing.
The Cure and the Consequences
The two plot threads — the mad scientist’s secret murders and the escaped-ape manhunt — collide in what more than one reviewer has described as a genuinely far-fetched final act, where Adrian’s efforts to complete Frances’s cure and the sheriff’s efforts to close in on the killer reach their climax simultaneously. Whether Adrian succeeds in curing Frances, and what becomes of him once the truth comes out, plays out in a resolution most critics agree is less important than the sheer novelty of how the film got there.
Ray “Crash” Corrigan — The Screen’s Go-To Gorilla
The ape itself was played, uncredited, by Ray “Crash” Corrigan, a stuntman and actor who built an entire side career appearing in gorilla suits across dozens of B-movies throughout the 1930s and ’40s — enough of a specialization that one retrospective simply labels him a “screen gorilla specialist.” One reviewer’s blunt verdict on the resulting costume — “as unconvincing and flea-bitten as you’d expect” — is echoed almost universally across assessments of the film, though most reviewers add that it’s entertaining precisely because of, rather than despite, how unconvincing it looks.
Where to Watch The Ape (1940) Free Online
The Ape is in the public domain and legally available across multiple platforms at no cost.
| Platform | Format | Cost |
|---|---|---|
| Internet Archive | Stream + Download (multiple formats) | Free |
| YouTube | Stream | Free |
| Public Domain Movies | Stream | Free |
The Ape (1940) on Internet Archive:
Is Ape, The (1940) in the Public Domain?
Yes. The Ape (1940) is in the public domain in the United States, and can be legally streamed, downloaded, shared, and screened without restriction or cost. It’s freely distributed by archival platforms including the Internet Archive, and is commonly found on public domain horror compilations alongside other Monogram-era Karloff titles.
Critical Reception — Then and Now
So the movie scores a 4.6 out of 10 on IMDb, which sorta mirrors how it’s remembered as minor, uneven B-horror that kind of limps along mostly on Karloff being there. TV Guide’s capsule review, says the whole thing is “corny but fun,” and honestly that’s a decent little shorthand for how later opinions tend to land. It’s genuinely silly, and the writing is a bit thin, but it’s rarely dull through its quick 62 minute runtime. Letterboxd users have taken to comparing it favorably against its closest genre cousin, noting that between Karloff’s The Ape and Bela Lugosi’s similarly themed The Ape Man (1943), “The Ape is the far more watchable one” — a reflection of the two horror icons’ frequent, and frequently unflattering, competition for the era’s cut-rate monster pictures.
The film’s most memorable feature according to nearly every retrospective isn’t its scares but its sheer strangeness — the mad-scientist-meets-escaped-gorilla mashup, and the gruesome detail of Adrian donning the literal skin of the dead ape rather than a simple costume within the story itself. One dedicated horror-history blog concluded its “enduring charm” comes precisely from how two mismatched studio mandates — Monogram wanting a gorilla picture, Siodmak wanting a spinal-fluid murder mystery — were awkwardly stitched together into a single 62-minute feature.
Frequently Asked Questions — Ape, The 1940
Q: What is The Ape (1940) about?
A kindly small-town doctor, Dr. Bernard Adrian (Boris Karloff), is secretly murdering local residents to harvest spinal fluid for a polio cure, while an escaped circus ape simultaneously terrorizes the same town. Adrian eventually disguises himself using the skinned hide of the dead ape to commit some of his own murders, letting suspicion fall on the animal instead.
Q: Is The Ape (1940) in the public domain?
Yes. The Ape is in the public domain in the United States and is freely available on the Internet Archive, YouTube, and other public domain film platforms.
Q: Who wrote The Ape?
The screenplay was written by Richard Carroll and Curt Siodmak (credited as Kurt Siodmak), based on a play by Adam Hull Shirk. Siodmak would go on to write The Wolf Man the following year, in 1941, cementing his reputation as a major horror screenwriter.
Q: Was The Ape Boris Karloff’s last film for Monogram?
Yes. The Ape was the final picture in a six-film contract Karloff had with Monogram Pictures, which also included five entries in the studio’s Mr. Wong detective mystery series, all directed by William Nigh.
Q: Who played the ape in the film?
The ape was played, uncredited, by Ray ‘Crash’ Corrigan, a stuntman who specialized in ape and gorilla roles across numerous B-movies of the 1930s and 1940s.
Q: Is The Ape based on a true story or earlier work?
The film is based on a play called The Ape by Adam Hull Shirk. The same source material had previously been adapted by the same director, William Nigh, as The House of Mystery (1934).
Q: How long is The Ape?
The film runs approximately 62 minutes.
Q: What did critics say about The Ape?
Critics generally describe The Ape as silly but entertaining B-horror, elevated significantly by Boris Karloff’s sympathetic performance despite thin writing and an unconvincing ape costume. It’s frequently compared favorably to Bela Lugosi’s similarly themed The Ape Man (1943).
Q: Where can I watch The Ape (1940) for free?
The Ape is freely available on the Internet Archive, YouTube, and Public Domain Movies. All versions are legal to stream and download under public domain status.
Related Free Classic Horror Films
If Ape, The (1940) drew you into Boris Karloff’s Poverty Row horror work, or into cheap-but-charming mad scientist pictures of the era, these are the natural titles to explore next:
- Public Domain Horror Movies – Free Classic Scary Films Online
- Dead Men Walk (1943) Full Movie Review, Plot, Cast & Free Horror Classic
- Strange Illusion (1945) Full Movie Review, Plot, Cast & Free Film Noir Classic
- Public Domain Movies List – All Free Classic Films (Complete Guide)
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