Edgar Rice Burroughs did not intended to write a trilogy, but his 1914 pulp novel The Warlord of Mars completes the story begun in A Princess of Mars and continued in The Gods of Mars and finally brings John Carter and his beloved Dejah Thoris, Princess of Helium (i.e., no cliffhanger this time around, boys and girls).
The characters are all extremely likable. John Carter is the perfect southern gentleman. Honorable, loyal, incredibly brave, respectful to women, extremely handsome; a perfect hero who is never boorish or conceited.
The story picks up six months after the conclusion of The Gods of Mars, with our hero not knowing whether she is dead or alive in the Temple of the Sun of the Holy Therns where he last saw here with the blade of Phaidor was descending towards her heart as the evil Issus, queen of the First Born, had locked his mate in a cell that would not open for another year. However, it turns out that the exiled leader of the Therns has reached the trapped women to rescue his daughter and to seek revenge on Carter for exposing his evil cult.
The focus of The Warlord of Mars is on Carter's relentless pursuit of the villainous Thurid who have taken his beloved princess from the south pole of Barsoom across rivers, desert, jungles, and ice to the forbidden lands of the north in the city of Kadabra where the combined armies of the green, red and black races attack the yellow tribes of the north, thereby justifying the book's title. It is interesting to note that Carter's heroics in this novel have the same sort of over the top implausibility we find in contemporary Hollywood blockbusters as ERB pours on the action sequences one on top of another. Whether he is scaling towers in the dark of night or surviving in a pit for over a week without food and water, John Carter is a manly hero in the great pulp fiction tradition of which Edgar Rice Burroughs was an admitted master.
Overall, the Martian series is Burrough's best work, avoiding the repetition that overwhelmed his Tarzan series and providing a lot more creativity (ever play Martian chess?).
