Two would-be grave robbers creep into a Welsh graveyard one night looking for treasures, and decide to break into the tomb of the dead-four-years Lawrence Talbot (Lon Chaney Jr). However, once inside they open his coffin and remove the wolfbane that had been placed there, Talbot begins to revive, grabbing hold of one of the robbers' arms. This is highly unfortunate for both him and Talbot, for the supposedly deceased man is actually the Wolf Man, and in that guise can never be killed - unless he can find a way that's linked to the Frankenstein Monster (Bela Lugosi)...
Curt Siodmak wrote this, the sequel to both The Wolf Man and Ghost of Frankenstein. Before you say, "Yeah, well, the Wolf Man actually meets Frankenstein's Monster" he also meets Frankenstein's daughter, here played by Ilona Massey, so the title does make sense. Probably the archetypal Universal horror of the 1940's, with its creepy graveyards, gothic castles, rhubarbing villagers and unusual mix of accents all set in a shadowy, fable-like version of Europe, it also began the shortlived and profitable strain of teaming up the monsters.
Chaney does well enough, noticeably recieving more of the limelight as Talbot escapes from the Welsh police and finding the Maria the gypsy (Maria Ouspenskaya) from his first Wolf Man film in what turns out to be a limited but oddly touching reminder of the father-son relationship from before, this time a mother-son one as Maria takes Talbot under her wing as a substiutute for her dead son, also a wolfman. Chaney gets to wear his makeup a lot more this time, and as a bonus there are more transformation sequences too, exhibiting Jack Pierce's skill with his art.
However, Lugosi gets a raw deal as the Monster as all of his dialogue was cut, and he doesn't get much to do except walk stiffly and growl where in a number of scenes he is patently replaced with a stuntman for any difficult physical stuff. In Ghost of... it was established that the Monster had Lugosi's character Ygor's brain transplanted into its head, but all that business was disposed off, perhaps because they thought nobody would recall that and it needlessly complicated the story, although continuity was never the series' strong point anyway.
The same echoes of the past that pursue the Frankenstein name, that is all that death and destruction, now haunt the Talbot name as well, and Chaney is appropriately distressed throughout. That Frankenstein name could explain why the village the characters end up in next to the castle is now called Vasaria. Though pitting these two icons against each other breathed new life into the formula, it was still the same formula for all that and innovations were getting thin on the ground. Also with: some of those bzzt things, and a musical number that seems to have wandered in from a Jeanette MacDonald and Nelson Eddy operetta - you may sympathise with Chaney's reaction. Um... wouldn't blowing up the dam destroy the village as well?