In Biggles in Australia, Roth was a Communist sleeper agent of von Stalhein's network in Australia.
Von Stalhein had turned up in Australia, ostensibly a survivor after his oceanographic ship the See Taube had been wrecked off the Northwest coast of Australia during a violent storm known as a "willy-willy". While investigating the reasons for von Stalhein's presence in Australia, Biggles and Ginger locate debris from a shipwreck on a remote island. Ginger picks up several sheets of paper. One sheet had a list of names and addresses which included Roth at a place called Tarracooma.
When Biggles arrived in Broome and called on Sergeant Bill Gilson, he asked the Australian policeman if he knew any of the names or places listed on the sheet. Gilson found out that Tarracooma was a sheep station about one hundred to one hundred fifty miles southeast of Broome and Biggles decided to fly there to question Roth, stopping by at the MacLaren Hills where they discovered the body of Joe Hopkins, who had been murdered.
At Tarracooma, Biggles and Gilson met Roth as well as Adamsen, another name on von Stalhein's list. Apparently he had been flown up to Tarracooma to help Roth fix his radio. As Roth was operating the radio without a licence, Biggles had the valves removed. Gilson noticed some belongings of Joe Hopkins' at Tarracooma and moved to arrest Roth and his associate Charlie. Both resisted but were overpowered and taken to Broome. They subsequently received long prison sentences for the crimes they committed.