Paul Féval, fils

Paul Féval fils' The Years Between series (French title d'Artagnan contre Cyrano) published in 1925 was written with M. Lassez and consists of four books: The Mysterious Cavalier, Martyr to the Queen, The Secret of the Bastille, and The Heir to Buckingham.

These books supposedly fill in the missing twenty-year gap of d'Artagnan's life that Alexandre Dumas, père omitted between his stories of The Three Musketeers and Twenty Years After.

In it, young Cyrano befriends a "Mystery Knight", who is revealed as the illegitimate son of the Duke of Buckingham and Anne of Austria, the Queen of France.

When civil war threatens, the two heroes are forced to side with the Queen, young Louis XIV and, to their dismay, Mazarin, against the rebels who want to use the Man in the Iron Mask.

Les Mystères de Demain takes a kitchen sink approach to the genre, using every cliché: hidden lair on top of the Everest, "carnoplastic" surgery, soul transfers, mountain dwarves, salamanders at the Earth’s core, germ warfare, the return of Atlantis, etc.

In 1929, Féval fils wrote Félifax, the story of the eponymous Tarzan-like, man-made hybrid tiger-man and his adventures in India and England, pitted against British detective and successor of Sherlock Holmes, Sir Eric Palmer.