Santo in The Grave Robbers aka Santo en los profanadores de tumbas shows our hero Santo investigating a series of grave robbings.
The film opens with four men digging up bodies in a graveyard. They take them back to a hidden laboratory. The leader, Dr. Toicher, says “Tonight was more fruitful than the others–the bodies are young and fresh.” If he can make one’s heart beat after 72 hours of death, he’ll have succeeded in his quest. One body begins to respond to the treatment, but suddenly there is an explosion: “Another failure! But,” Toicher adds optimistically, “with each failure we learn something. We need the heart of a superman, and I’ve located him.” “Who is it?” one of his henchman asks. “You’ll find out soon,” is the doctor’s reply.
Santo is reading a newspaper: “Grave Robberies Continue.” He checks out his extensive library of interesting subjects: “Human Vampires,” “Stranglers,” and “Grave Robbers.” A delivery boy arrives with a present from Santo’s friend, Carlos. While Santo is distracted, Toicher’s hunchback assistant sneaks into the apartment. The present is a lamp with a strange shade: pictures of bizarre, contorted faces, and a large human heart. Plugging the lamp in, Santo is assailed by a strange noise which drives him to his knees. Meanwhile, the hunchback steals a set of keys, and leaves, unseen. Santo manages to turn the lamp off, and discovers that the designs are painted in “human blood!”
Outside, the hunchback is punished by Toicher for acting on his own. The hunchback says, “I wanted to help you out by capturing Santo, so you could have his heart. Then I thought you would let me have his thyroid,” which would cure his condition. He claims his diabolical devices can do the trick-Toicher says he doesn’t need any of the hunchback’s inventions.
Santo calls Carlos, but his friend, a professional soccer player, has a match that day. Santo leaves to meet him at the stadium, and he is observed by Toicher and his men, who enter his apartment after he is gone.
After the soccer game, Santo greets Carlos in the players’ parking lot. He asks if Carlos sent him the lamp, but his friend denies it. Santo says he didn’t really think so, it was just a trick to get him to take the package. They go back to his apartment to look at the bizarre device, but it is gone, along with a duplicate set of house keys. Why? Santo suggests it might be connected with the grave robberies, and Carlos is involved because he is Santo’s friend. Carlos hopes his fiancée Marta isn’ t in any danger.
Marta is a nightclub singer. After her number, the trio Los Chavales perform, while Carlos talks to Marta in her dressing room. He’ll protect her in case of any danger, and they’ll see Santo the next day.
Santo is at the arena the next evening, wrestling. Carlos and Marta are in the audience, as are Toicher and his hunchback aide. Toicher still wants Santo’s body, but he also craves the use of Carlos and Marta’s corpses. Santo wins, and even his opponent is proud to have lost to such a great competitor.
Toicher resumes his experiments: “Another failure!” The body was young, but it wasn’t healthy. “Perhaps the person died of cancer, or some disease. We need bodies that died in accidents, perhaps were suffocated or drowned. The best way is to kidnap them alive, and kill them ourselves. That’s what we’ll do with Santo.” “It can’t be done,” his sidekick protests. Yes it can, Toicher says. He has a plan, and will put it into effect the next day, by calling Santo on his private line.
Toicher’s spy reports that Santo has arrived at his house. Toicher calls Santo, and has Gorila tell him that he can catch the grave robbers that night at midnight at the municipal graveyard.
The employees of the nightclub where Marta works received an invitation to visit a special curio shop, which is having a sale. The maitre d’ is also a painter, and he buys some paint; the violinist buys a new violin; Marta buys a wig. When they leave, the store manager calls Toicher and reports that his plans have succeeded.
That night, Toicher and his men are digging up a body when Santo arrives. After a battle, Santo is knocked into an open grave, and buried alive. However, he manages to grab Toicher’s hat as he falls. When the grave robbers have gone, Santo digs himself out. Inside the hatband he sees the words: “Dr Toicher, Paris.” Calling Paris on his radio, Santo asks his agent to contact Interpol and check on Toicher, “who is probably of Slavic origin, but spent time in Paris.” However, Toicher’s spy sees Santo is alive, and reports to Toicher.
The doctor is planning to use Marta and Carlos for his experiments. When he gets the word Santo is still alive, he is pretty mad at his assistants: “Santo is alive! This is the limit!! It’s your fault, you’re clumsy animals!”
Paris calls Santo back. Toicher is a dangerous criminal; they will send an Interpol agent to meet Santo with information about his activities. Santo contacts Carlos and asks him to bring Inspector Mendoza to meet him in secret. He has important information about the grave robbers. When the two men arrive at Santo’s house, Toicher’s spy reports. When the Interpol agent arrives, Toicher’s men kidnap him, despite a neighbour of Santo raising the alarm. Santo: “We know now we’re facing super-criminals.”
The nightclub violinist is playing for rehearsal when his violin suddenly seems possessed: the strings try to strangle him, and the violin hops around and finally explodes!
Toicher has made a decision: “We have to finish Santo. His body is the only thing that will allow me to finish my experiments. Otherwise, we will fail utterly.” “It won’t be easy,” Gorila says. “My genius will conquer his strength!” Toicher predicts. Toicher orders the hunchback to stick Santo with a needle during a wrestling match: the poison will first turn him into a human beast, then will kill him. However, at the wrestling match the hunchback slips and accidentally injects Santo’s opponent. The man goes wild, then collapses and dies. Santo tells Mendoza: “He didn’t take any blow that would have caused that reaction,” but then he finds the needle mark that proves his opponent was poisoned.
Toicher is angry at the new failure and orders the hunchback killed, but his deformed aide begs for one more chance. Toicher says he has to have Marta, Carlos and Santos that night. The hunchback says “The killer wig will help us.”
Marta, wearing the wig, does her musical number, but the wig comes to life and starts to strangle her. Santo, disguised as a nightclub customer, jumps in to save her, and tangles with Toicher and his men. Someone turns off the lights, and the villains escape. Santo saves Marta and warns Carlos: “We need to be careful: these criminals will stop at nothing.”
Toicher is mad again, but his men protest: “Santo is indestructible.” “Nothing is indestructible except the genius of someone like me. I need the bodies of Santo, Carlos and Marta. If not, I will fail, but you will first pay for your ineptitude with your lives.”
The portrait painter paints a young girl with the special paint; the picture is horrible and begins to leak blood. Marta, the violinist, and the painter all complain to Mendoza, telling him of the curio shop where they purchased the evil devices. Toicher and his men are busy destroying corpses when a call comes in: the shop manager says the police are outside. Toicher orders him to lock the doors and windows and wait for help. Then, he blows up the shop by remote control. A henchman asks: “What about the manager?” “Don’t get sentimental,” Toicher snaps.
Carlos has another soccer match. Afterwards, he and Marta are talking in his car. They are assaulted by Toicher’s men, but Santo–disguised as a chestnut vendor – saves them. Toicher says he will try once again to capture Santo, and if this fails, he’ll put his henchmen in the disintegrating chamber. They plant the killer lamp in Santo’s apartment, and then – pretending to be Santo – call Carlos and tell him to bring Marta to the apartment. The lamp knocks Carlos and Marta out, and Toicher and his men carry them off. Santo arrives and is nearly overcome by the lamp, but manages to wrestle it to the ground and destroy it. He sees the chloroform used on Carlos and Marta.
Paris calls and Santo reports that the Interpol agent was murdered, but says he will capture those responsible. Toicher orders Marta to read a note to Santo over the phone: “You must come at midnight, alone, or we will die.” She gives him the address. Santo goes to the hideout and is knocked out by an electrified grid. Toicher’s men put him in an airtight chamber where he will die in three minutes. Toicher prepares to operate on Carlos and Marta, promising the hunchback the thyroid as a bonus. Santo escapes from the chamber and fights Toicher’s henchmen, killing them both. Toicher hears the screams, and starts to see what is up, but the hunchback insists he continue the operations: Toicher kills him. Santo faces off with Toicher and the mad doctor is finally killed. The police arrive. Santo says “The days of the grave robbing gang are over.” Mendoza says “All criminals have to pay for their crimes: it’s an end no criminal can escape.” Carlos: “Especially since Santo is on the job fighting evil, wherever it may be.”