The Invisible Ray

In the living room of Rukh Castle, located in the Carpathians, Dr. Janusz Rukh's mother and his wife, Diana, are talking, waiting for the arrival of foreigners to whom the doctor will demonstrate his inventions. In the conversation, the doctor's mother mentions that she went blind during one of her son's previous experiments. A car appears on the road, and Diana goes to the astronomical laboratory to notify Dr. Rukh of the arrival of guests.

Dr. Rukh shows the guests - Sir Francis Stevens, his wife and her nephew, and Dr. Bene accompanying them - his modified telescope, as well as information about the Earth's past, obtained by him with the help of this telescope from a beam of light from the Andromeda nebula. In particular, the scientist's long-standing theory about a meteorite that fell in Africa containing a very strong source of radiation is confirmed.

Two months later, Dr. Rukh, as part of an expedition equipped by Sir Stevens, finds in Africa the site of the fall of a meteorite consisting of a radioactive substance unknown to science. After contact with the substance, the doctor acquires extraordinary abilities: he begins to glow in the dark, and those he touches die.

Dr. Bene is developing an antidote for Rukh, and now he has to take it regularly, otherwise the symptoms will return. To relieve symptoms, Bene makes a stock of an antidote. Meanwhile, Rukh is studying the possibilities of a substance with enormous energy. With the help of a small amount of it, the doctor creates a weapon capable of destroying entire cities. At this time, the rest of the expedition members leave Africa. Sir Stevens leaves for a scientific symposium, where he and Dr. Bene present the discovery of the Rukh. Diana Rukh, who has fallen in love with Ronald Drake, is also leaving.

Feeling cheated and robbed, Dr. Rukh returns to the Carpathians, where he discovers the ability of a substance (called "Radium X") to heal and returns his mother's sight. Dr. Rukh goes to Paris, where he meets with Dr. Benet, who made the same discovery and successfully treats patients. Dr. Bene reports that Dr. Rukh has been awarded the Nobel Prize for the discovery of radium x, but Rukh is not interested in this. After learning that Diana has become Lady Arabella's secretary, he leaves the Bene Clinic. Dr. Rukh fakes his death and then quietly watches the wedding of Diana and Francis. Soon after, Sir Stevens is found dead, and Dr. Bene identifies Dr. Rukh as his killer from the postmortem image in the eyes of the deceased. Lady Arabella dies soon after. Dr. Bene discovers glowing fingerprints on her neck and tells the police about his suspicions.

Bene suggests setting a trap for Rukh by announcing his lecture on radium x, where he and Ronald Drake and Diana will be. The lecture is scheduled to take place at midnight. Rukh enters the building unnoticed and kills Bene. Dr. Rukh's mother comes to the lecture. At the same time, at midnight, the lights go out all over the house – this is a trap to catch the Roc glowing in the dark. Dr. Rukh is going to kill Diana, but he can't– he still loves her. On the stairs, he meets his mother, and she breaks the remaining bottle of antidote. Rukh, who did not take the drug in time, jumps out of the window and burns from the inside.