[citation needed] In the same year, the transfer of the mortal remains of the missionary Damien de Veuster from a Hawaiian leper colony to his native Belgium inspired Hünermann to compose a biographical novel about him (Priester der Verbannten).

Be that as it may, the novel was soon translated into numerous European and non-European languages, and also determined his writing orientation for the rest of his life: except several plays and short stories, the author almost entirely dedicated himself to the saints’ biographies.

His works sold more than three million copies and were translated into over twenty languages, primarily French, Spanish, Slovene, Croatian, Polish, Czech, Slovak, Hungarian, Lithuanian, Romanian and Dutch.

Before and during writing his biographical works, he thoroughly studied the bulk of available material concerning a certain person, from newspaper articles to diary notes, letters and existent biographies, and tried to incorporate each interesting detail or testimony into a harmonious whole.

Among the most persuasive of his creations are Die Herrgottsschanze, the 1940 novel about the priest Peter Coudrin, active during and after the French revolution, which at the time of publication was actually a call for the underground resistance to Nazism; Vater Kolping: Ein Lebensbild des Gesellenvaters, a socially committed work on Father Adolph Kolping; Um Mädchenehre, a moving story about a contemporary martyr for chastity, Maria Goretti that was published on the occasion of her canonization; and an exceedingly lively and impressive portrait of the French village priest Jean Vianney, Der Heilige und sein Dämon.