Una cajera de banco desarrolla un elaborado plan para robar dinero de la bóveda donde trabaja.

Capulina is a night-watchman in a warehouse, a perfect job for him. When some thieves break in and steal some crates, El Santo is after them because they are using the warehouse for diamond smuggling. Capulina hinders their capture. He then decides that he will put on a wrestler's mask and help El Santo to caputre the crooks.