Tarzan the Invincible

Tarzan the Invincible was published in 1931 and is one of the more politically engaged books in the sequence. The plot involves a Soviet expedition into the African interior, ostensibly archaeological but actually intended to loot the gold of Opar and provide propaganda material against the British colonial presence. The expedition is led by a Russian commissar named Zora Drinov, who is unlike most Burroughs antagonists in being competent, complicated, and capable of changing her mind.

Tarzan opposes the expedition, but with less unmixed enthusiasm than he would oppose, say, German colonial officers. The lost city of Opar reappears, with La once again involved. There is a subplot with a young American couple, Wayne and Jane Colt, who get drawn into the Soviet expedition by accident. Zora Drinov ends up as one of the more interesting recurring secondary characters in the series. The book's political content is dated but unusually nuanced for Burroughs. Solid late-period entry.