Erik, in love with Magda, the fiancée of Georg, his boss, secretly sends her roses every night.
Shortly after his return from India, a special agent of the British secret service falls victim to an insidious poisoning in London. Scotland Yard gets involved. But too late: valuable information has fallen into the hands of an international criminal gang...
A scientist discovers the formula of a particular resistant steel, and a spy ring from an enemy power sets after him to obtain it.
