Felix Salinger is the narrator and protagonist not only of After but also of all seven books in Gleitzman’s Once series. This particular installment, which is chronologically the fourth book in the series, begins on Felix’s 13th birthday in the winter of 1944-1945. For two years prior to the beginning of After, he lived in an earthen hole beneath the stable in Gabriek’s barn in Poland. With Gabriek’s protection, Felix hides from the Nazis who occupy Poland and prioritize the arrest of any Jew. Felix’s parents were Jewish booksellers and have long since been captured by the Nazis and transported to a death camp. For the majority of the narrative, Felix assumes that they are dead.

Able to emerge from his hiding place for just a few minutes at night, Felix interacts only with Gabriek, who brings him food and reading material and teaches him a variety of lessons. Felix’s cramped quarters have affected his development, particularly impacting his legs, though his hearing and sense of smell have become more acute. Felix wears glasses that are broken and fitted with a four-year-old prescription. Midway through the narrative, Yuli brings him a sack of glasses—formerly belonging to concentration camp captives—from which he chooses a new set.