During the Spanish Civil War, D a middle aged, former prisoner of war who recently lost his wife in the conflict arrives by boat in Dover, England having business to conduct with Lord Benditch. By chance he encounters Benditch's daughter, Rose Cullen, at the customs inspection. She offers him a ride to London but they are forced to stop for dinner while having a tire replaced.
At the restaurant D. spots a rival agent, L, who is employed by the rebel faction of his nation. L's driver accosts D in the toilet. D borrows Ms. Cullen's auto, but is chased down by L, his chauffeur, the manager Mr. Currie, and Ms. Cullen. He is savagely beaten, then set loose on foot to find his way to London.
Arriving at his hotel he befriends a maid named Else, and learns he has an appointment that day at a language class for Entrenationo, a would-be universal language. Mr. K is actually his contact in London posing as an instructor. On the street D is fired at, when suddenly he meets Ms. Cullen again. She claims ignorance of the plot. He tells her of his former life as a scholar and lecturer, and how he was widowed and imprisoned during the war. They have dinner and see a show. He and Ms. Cullen begin to have feelings for one another.
Else has also fallen for him and shows some jealousy over his relationship with Ms. Cullen. He wishes to assist her in a fatherly way. D is interrogated by the manageress and K, both of whom are looking to profit by selling out D's credentials to L and the rebels.
By the time D has his meeting with Lord Benditch and several coal proprietors, his papers are missing. He drives with Ms. Cullen and Forbes, a wealthy mine owner who has asked for her hand but has a mistress. They arrive at the Spanish Embassy where the First Secretary accuses D of having a forged passport, as the picture is poor and bares only a slight resemblance. When the police are summoned, D learns that Else has been murdered and he is implicated.
His passive nature vanishes and he resolves to make those who have killed the girl pay dearly. He slugs the detective and takes possession of his gun. D flees the embassy in the fog and finds an unoccupied flat to hide in. He shaves his moustache and evades capture. He sets out to the hotel to confront K and the manageress. He views Else's corpse in his room before following K out of the hotel to the Institute of Entrenationo where a soiree is taking place. He leaves with K and is able to take him away by taxi to the abandoned flat to question him further. D tries to shoot him but hasn't got the nerve, missing him by a foot or so as Ms. Cullen appears at the door. They discover K has died from fright and laid him out on the divan.
D learns that L has received the coal commission he so badly needed from Lord Benditch for his people. He departs on the evening train heading north to the town of Benditch seeking assistance from the miners. Hoping to convince them to reject the order to opening the mines, he is to meet Bates the local mineworkers representative in town. He makes his way to the Red Lion Inn and finds Bates is meeting with none other than L! D speaks to Bates, telling him the truth about the destination of the coal. Bates is unable to be swayed, so D addresses the crowd until the police are called. D flees but finds he has friends at hand and they help him elude capture hiding him and using his gun to steal dynamite to close the mines. The dynamite doesn't finish the task as D is caught and taken to London due to the lengthy list of charges facing him. He is bailed out of jail by Forbes, who acting on Ms. Cullen's wishes, takes him to a seaside-resort for his eventual repatriation to Spain. At the bar, Currie spots D and is detained until the police can arrive to take him back to London. Two men escort him out of the resort to an uncertain fate.
This report prepared by David Fletcher