Answering a call for help by letter from an old friend, Biggles, Algy, Ginger and Smyth fly to Fort Beaver in Canada. Here they intend to meet up with Wilks, or Captain Wilkinson of 187 Squadron as he used to be known. Wilks has started a small airline business called 'Arctic Airways' but is now having problems with a man named 'Brindle' Jake McBain and his cronies. On arrival, Biggles finds Wilks is missing and immediately crosses swords with McBain who is "sharing" Wilks' aerodrome, but in reality is really an unwanted trespasser.