Chapter 1: An Interrupted Cruise[]
Biggles, accompanied by Algy and Ginger, is making a sea voyage in the Mediterranean on doctor's orders in order to recover from a bout of fever. Passing the coast of Spain off Barcelona, the ship is attacked and sunk by an unknown aircraft.
Chapter 2: A Swim in the Dark[]
After paddling for a long time in lifebelts, they come ashore at Barcelona and make their way to a cafe for a hot drink and meal.
Chapter 3: A Dangerous Mission[]
Inside the case, they meet Dicky Frazer, a former R.F.C. officer and now a British agent. Frazer is in a quandry. He was here to meet a contact but he has been killed. Outside an enemy agent Juan Goudini has laid an ambush for him. He has an urgent paper which must be delivered to the British Foreign Office. He knows he will be killed by Goudini as he leaves, so he asks Biggles to help deliver the document. Biggles agrees so Frazer slips the envelope to him and they leave by the back way through the kitchen. Frazer steps out the front entrance where he is killed by shots.
Chapter 4: Unexpected Developments[]
Out through the back door, Biggles, Algy and Ginger also find their way barred by some men at both ends but suddenly a car crashes through, scattering everyone. The car stops by Biggles and a stranger asks them to get in. Puzzled but nonetheless grateful for the rescue, they clamber on board. The stranger takes them to a room in a small hotel and then his motives emerge: he pulls a gun and demands Frazer's document.
Chapter 5: Goudini Again[]
The stranger is a free-lance agent working on his own account. He had followed Frazer all the way from Rome and had seen him pass the paper to Biggles. Biggles has few options but just then the lights of the hotel go out: there is an air raid! Under the cover of the sudden darkness, Biggles crawls through a door into the bathroom. The lights come on and the stranger opens the door and demands the letter but Biggles tells him he is tossing it out of the window to the hall porter below and releases the document.
The man rushes downstairs and manages to get the paper from the poorter but Goudini arrives and shoots him dead. Upstairs, Biggles still has the important document--he had only thrown out the envelope!
Chapter 6: A Difficult Situation[]
But they had been locked in so they had no choice but to wait. Meanwhile Biggles rolls the paper into a ball and throws it onto a heap of rubbish down below. Goudini soon comes up--he introduces himself as the "Deputy Commissar Special of Intelligence and Propaganda" in Barcelona and has them searched. He can't find the document and so arrests them and takes them to a lock up at a barracks.
Chapter 7: A Nasty Shock[]
Biggles hears an American voice outside the window of their prison cell and manages to attract his attention. He turns out to be a volunteer soldier in the International Brigade. Biggles persuades him to get a file or hacksaw and he agrees. Biggles has some doubts about the American but he comes through with the tool. Our friends cut their way out during the night and even manage to get themselves into some International Brigade uniforms from the barrack stores.
They make their way to the rubbish heap near the hotel and retrieve the paper, only to see a score of Spanish Guardia Civil converging on them: it had all been a trap laid by Goudini!
Biggles tosses the ball of paper to Ginger who makes the cricket catch of his life and then sprints away into the city streets.
Chapter 8: Ginger Goes Alone[]
Pursued by soldiers, Ginger stumbles into a plaza full of International Brigade troops loading into trucks and he himself is bundled into one and taken to the front. There he is befriended by a fellow English volunteer, Fred Summers, who shows him the ropes of trench warfare.
Chapter 9: A Lucky Combat[]
For the next two days, Ginger has no choice but to play his part as an infantryman defending his section of the trench from attack by Nationalist troops. During one of the battles, a Republican fighter crashes into no man's land not far from his position. Gingercan hear the calls of the pilot and, motivated by the instinct to save a fellow airman, he crawls to the wreck and cuts the pilot free.
The pilot he saves is a Scot, Jock McLannock. When he hears that Ginger is a pilot he decides to enlist him in his squadron.
Chapter 10: More Shocks for Ginger[]
Jock takes Ginger up for a check flight in a two-seater when they are bounced by three Nationalist Fiat fighters. Ginger impresses Jock by shooting one down and sending the others retreating.
Back on the ground, Jock asks who had taught him to fly and seems startled when Ginger mentions "Biggles". Jock then him to his office and pulls out a gun. "What's the matter?" Ginger asks. "I'll show ye what's the matter, ye spyin' rat." Apparently Jock had read about Biggles, Algy and Ginger in a Barcelona newspaper and they had been named as spies. Ginger tells Jock the whole story. Jock believes him but tells him te bad news: according to the newspaper, Biggles and Algy were due to be executed in the morning.
Chapter 11: Back to Barcelona[]
Ginger hands Frazer's document to Jock, asking him to deliver it if he fails to return. In the meantime, he borrows Jock's gun and car and dashes off to Barcelona. Arriving in the dark, he can't think of a good plan to rescue Biggles and Algy who are being held on a ship, the San Christophe. However, by the quayside, he spots Goudini getting into a car and instinctively holds him up with his gun.
Chapter 12: A Desperate Expedient[]
Ginger drives his prisoner out of the city and forces him to write a letter authorising the commandant on the prison ship to let him interrogate the British prisoners as an interpreter. Goudini obeys but then draws a knife and flings himself at Ginger. Ginger fires instinctively and hits Goudini. Ginger binds up his wounds. He doesn't want to leave the wounded Goudini to die but before he can do anything, he is forced to flee by the approach of some passers-by.
Chapter 13: A Memorable Night[]
Armed with Goudini's letter, Ginger tricks his way on board the ship and into Biggles' and Algy's cell. They escape and make their way back to Jock's airfield. There they hear shattering news: Jock has been shot down over enemy lines and Ginger is sure he was carrying Frazer's paper!
Chapter 14: Winged Warfare[]
Jock had gone down near the village of Ortrovidad. Biggles, Algy and Ginger discuss and decide that they must go across the lines after Jock and try to retrieve the document. There's a captured Caproni bomber at the airfield which would suit their purpose. Biggles and Algy get on board but Ginger is called away. Cy Harkwell, an American volunteer has taken over Jock's flight and wants Ginger to join him in a patrol.
Not wanting to create suspicion, Ginger follows Harwell and takes off in a fighter. He sees the Caproni has also taken off, heading for Ortrovidad.
Chapter 15: A Tragic Error[]
Ginger finds a convenient moment to peel off from his formation to join the Caproni. To his consternation, Cy Harkwell and the other flightmates follow him and start attacking the Italian bomber. Biggles and Algy obviously can't return fire and neither can Ginger interfere. A flight of Nationalist Fiat fighters join in to defend the Caproni, turning the sky into a confused dogfight in which Ginger shoots down a Fiat. He spots the Caproni heading away and dives after it. Too late, he discovers that it's the wrong bomber! The gunner fires at him and sets his fighter on fire, forcing him to bale out.
Chapter 16: In Deep Waters[]
In the Caproni, Biggles and Algy see Ginger being shot down. They land to help but are promptly captured by some Italian troops and are taken to a prison camp for questioning. Their interrogator knows all about them--he tells them Goudini, besides being a top Republican official, was also the Nationalist chief spy in Barcelona. Now, apparently he had been killed. Biggles' questioner wants Frazer's letter but Biggles doesn't have it and doesn't know where it is. He is given one night to "think better of his decision" and then taken away with Algy.
Chapter 17: An Unexpected Meeting[]
After his parachute landing, Ginger spots Biggles and Algy in a passing car. They have been captured! He steals a motorbike and follows them. On the road, he discovers Fred Summers, now a prisoner-of-war, engaged in some road works. Ginger offers him a lift and they tail Biggles and Algy to a prisoner-of-war camp where, according to Summers, Jock is also an inmate. Ginger decides that he must get into the camp in order to break his friends out. So, grabbing some tools from the motorbike, he and Summers sneak in by mixing themselves among the prisoners from the road works gang.
Chapter 18: Behind Barbed Wire[]
Summers and Ginger break Biggles, Algy and Jock out and they head for where Biggles had landed his Caproni.
Chapter 19: A Bitter Disappointment[]
The Caproni is not there! But Biggles hijacks a car with two Italian pilots. He takes the car and their uniforms and the rest pile in and head for the nearest Nationalist airfield. With Biggles and Algy dressed as Italian officers, the party is able to steal a Caproni bomber and head for France. Nearing the border, the aircraft is intercepted and hit by some pursuing Fiat fighters but Biggles is able to crash land the bomber just on the other side of the frontier.
Chapter 20: Adios--and Au Revoir[]
Our friends return to Britain and Biggles delivers Frazer's paper to the Foreign Office. "What did they say," Ginger asks. Biggles tells him: "Thanks very much."