The Gavins claimed the plot "followed closely the facts contained in the official report of the British Admiralty" about the Fryatt incident, with a Belgian love story added.

[6] The film begins after Fryatt, the commander of a merchant ship, has rammed a German submarine, and has returned to London a hero.

[9] Fryatt's murder was one of the three best known German atrocities of World War I, the others being the sinking of the RMS Lusitania and the execution of nurse Edith Cavell.

Gavin sought official approval from the New South Wales Chief Secretary prior to making the film.

"[15] During filming a sequence in North Sydney where soldiers raid a haunt of German spies, some bystanders joined in and had to be restrained by the police and John Gavin from smashing the plate glass in front of the shop.