First off, who the h*ll is Ingagi? He/she/it is not mentioned at all in this film. Well, Ingagi is an African gorilla and the title character of the 1930 B-movie Ingagi. No one connected with the first movie -- not the director, writer, producer, actors, no characters -- has anything to do with Son of Ingagi.
Secondly, this film is of historic note, if only because it is (debatedly) the first all-Black horror film made. That's a good thing and a bad thing. Good because it's a mildly entertaining piece of history; bad because of its low budget, sometimes amateurish acting, multitude of plot holes, and predictable storyline. Also the only (?) surviving print of this movie has been cut by about ten minutes and it really shows.
The plot: Eccentric Dr. Helen Jackson (Laura Bowman, Drums o' Voodoo, Murder in Harlem) has a reputation as a mad person and a "black magic" woman. Once she was in love, but her object of her affection married another and she left the country immediately after their wedding to become a missionary in Africa. Returning to America, she brought with her $20,000 in gold and an apeman companion. Wait. What? Yes, an apeman, but not just an apeman -- a giant, hunchbacked, simple-minded apeman named N'Gina (Zack Williams, 1929's The Four Feathers, uncredited role in Gone With the Wind). Of course the apeman is hidden in her (also hidden) basement and secret laboratory. Dr. Jackson is working on a medical discovery that will be the biggest advance in medicine since Pasteur (her own words) and a benefit to all mankind. We have no idea what this discovery is because it doesn't matter since N'Gina drinks the only test tube containing the wonderful discovery. This boon to mankind turns N'Gina into a homicidal apeman. (The effects may be intermittent, because for most of the rest of the film N'Gina is his simple-minded shambling old self except on occasion when he lackadaisically kills a few other people.) Jackson has a prominent lawyer (Earle Morris, The Bronze Buckaroo, Mystery in Swing) and an ex-con brother (Arthur Ray, Mr. Washington Goes to Town, Professor Creeps), both of whom are trying to get her hidden gold.
Backtracking a bit, the movie begins with the wedding of beautiful Eleanor (Daisy Bufford, uncredited role in Gone With the Wind, uncredited role in Charlie Chan in the Chinese Cat) and fashion mishap Bob (Alfred Grant, Golden Boy, The Vanishing Virginian). Turns out Eleanor is the orphaned daughter of Dr. Jackson's former love and (unknowingly) the sole heir in the doctor's will. It also happens that their house is next door to Dr. Jackson's and within viewing distance of foundry where Bob works (and where he was to go to work the day after his wedding). Unfortunately the foundry blow up (offscreen) on Bob's wedding night, so Bob starts off marriage unemployed.
That's basically all you need to know, but here are some highpoints of the film.
Bob and Eleanor's house has knotty pine walls and a knotty pine door so it looks like there are big black eyes all over the place.
The vocal quartet The Toppers, along with some friends, crash the wedding night for a party with strange dancing (both with and without music). The Toppers sing "So Long, Pal" and "You Drove the Gloom Away," Pleasant music which sounds nice but nothing to advance the plot.
N'Gani sleeps on a cot in a cage but the cage door is always unlocked, but they have to establish the cage for the film's ending.
Did I mention that Dr. Jackson creates a formula that will change medicine forever, but that we never know what the formula does? Besides make N'Gani homicidal, that is. Also, she's the most unscientific scientist evaah. (Nonetheless, Laura Bowman is the second most interesting acto in the film.)
The most interesting actor? Spencer Williams (Andy in television's Amos and Andy) plays the bumbling plain clothes detective Nelson. He's the comic foil but his schtick with the disappearing sandwiches is entertaining. (And he leaves the refigerator door open when he leaves the kitchen.)
N'Gani is the quietest apeman ever. Nobody hears him moving around the house. In fact, nobody sees him (despite his frequent excursions to raid the refrigerator) until it's too late.
Gunshots in the basement can be heard on the second floor, but not on the first. Also, there's selective hearing while people are screaming.
I really, really want Bob's sports jacket and tie but Kitty (she of good taste) won't let me get it.
Six bullets cannot stop N'Gani. In fact, they don't really bother him, although an itty bitty finger cut does.
N'Gani's make-up earned the film an Oscar nod. Not.
Except for the dead people, all ends well.