As I understand it, this movie was a huge, huge hit. It certainly deserved to be. Compared to other, early-1940s horror movies, this sucker is lightning in a bottle.
This is a sequel to The Mummy's Hand, released two years earlier. In that movie, Steve Banning and his unbearably komikal sidekick, Babe, discovered an Egyptian tomb guarded by a wizard and his pet mummy. That was thirty years ago, circa 1912. Circa 1942, Steve Banning is now old, a widower, and retired. (The old age makeup is little more than flour to make the actor's hair grey but, darn it, it works better than it has any right to.) His son, John, is a doctor all set to join the Army Medical Corps and do his duty in WWII, plus John's got a beautiful fiancee, Isobel, to boot. Yep, things sure are looking good for old Steve Banning and his family.
Unfortunately for him, the old wizard from The Mummy's Hand isn't dead after all, and he's spent the intervening thirty years raising a new High Priest of Karnack. The mummy, Kharis, wasn't destroyed either, and the old priest sends the new priest and Kharis to the U.S. to get revenge on the Banning family. (Incidentally, you can't tell me this scene wasn't somewhere in the back of George Lucas's mind when he was writing Return of the Jedi. It's eerily similar to the part where Yoda passes the last Jedi torch to Luke.)
The new priest, Mehemet, indeed travels to the United States, where a job as the cemetery keeper has already been arranged for him. He sics Kharis on old Steve Banning immediately and, shockingly, Kharis finds and kills him! You can imagine how much of a shock it is to Banning when a nightmare from a lifetime ago crawls through his window and wraps his unnaturally powerful hand around his throat. Now just imagine what a shock it must have been to audiences! This isn't a 1970s movie, when that kind of thing was expected, this is a 1940s movie! I'm willing to bet nothing like that had played across movie screens since Mr. Hyde murdered Ivy all the way back in 1932. How I wish I could have been a little kid seeing this in a Saturday matinee back then.
Banning's death brings Babe crawling out of the woodwork. In The Mummy's Hand babe was a generic comic-relief character, Brooklyn accent and all. Here's he's older, gruffer, and not one "joke" passes his lips. Once he hears that there was strange mold found on Steve's throat, he knows exactly what's going on. The next few minutes of movie time are spent on Babe frantically trying to get someone, anyone to listen to him. Eventually, he too runs afoul of Kharis. His death scene is a highlight of the film. At first, Babe seems to grimly accept his fate. Then he has a change of heart and tries to flee. Unfortunately, he corners himself in a blind alley ... so he tries to fight! Victims in 1940s monster movies usually aren't so proactive.
Meanwhile, Mehemet (who, let's not forget, has spent most of his life in an ancient tomb with a crazy old man) has started to notice there are things called "women", and that he kind of likes them. In particular, he's decided he likes Isobel. Throughout the movie, Mehemet has been following John around. John spends a lot of time with Isobel, naturally, so Mehemet has been privy to all sorts of lovey-dovey scenes between them. It's even strongly implied that he watched them have sex. Well, Mehemet decides that when John dies, he will claim Isobel as his own. The next time he animates Kharis, he sends him out not to kill John Banning (the last remaining target), but instead to capture Isobel. This is without a doubt the best part of the entire movie. While Mehemet prattles on about how Isobel's womb will be host to the next High Priest of Karnack, Kharis's body language perfectly communicates his feelings on the subject: "Are you f**king KIDDING ME? This is the exact same s**t that got me set on fire in the last movie!"
Unfortunately, what remains of Kharis's will is not enough for him to disobey Mehemet, so off to abduct Isobel he goes. And, sure enough, this action leads to his and Mehemet's defeat. There's another great moment while Kharis is carrying Isobel away. Seeing a torch-bearing mob coming to kick his ass, he slouches in resignation. "Yep. Gonna get burned up again. Damn it."
The Mummy's Tomb still holds up today as an excellent example of how to make a low-budget monster movie. The storytelling is economical and extremely effective. The characters are only lightly sketched but you know everything you need to know about them. There are no plot holes. The closest the movie gets to one is not explaining how, exactly, Mehemet's position as cemetery caretaker was set up but, really, that doesn't even matter. Everything that happens does so for readily defensible reasons. No one does anything stupid. The movie is even clever enough to have a scientist be the one to confirm that the killer is of supernatural origin! And, let me remind you, this is a movie from the 1940s that killed off the heroes of the previous film (and a sweet old lady, to boot)! And let's not forget Jack Pierce's excellent makeup job on Kharis. There still hasn't been a better looking movie mummy in all of 70 years.
Oh ... and one more thing ... there is no comic relief. None. Zero. Nada. Zip. This is a movie that remains deadly serious throughout while still being a great deal of fun.
Before I go, let me draw attention to something that might possibly make this the most influential body-count movie of all time. The first time Kharis goes out to kill, he passes by a car. A parked car. A parked car with two teenagers inside, making out. The girl says, "Hey! What was that?" The guy says, "I didn't see anything." I can't think of an earlier horror movie to use this scene but for the next sixty years, at least, it was hard to find one that didn't.
This cheap little b-picture is certainly still the best mummy movie ever made and stands toe-to-toe with all but the very best of the classic Universal horror movies overall.