El misterioso señor Brown

The search for compromising secret documents, signed during the First World War and lost in the sinking of the Lusitania, gives rise to a merciless fight between the British secret services and an international gang that wants to use the documents as an instrument of Bolshevik propaganda. But in the maelstrom of the spy war, two young men appear, Tommy and Tuppence, ready to risk their lives to reveal the identity of the gang's leader, the mysterious Mr. Brown.