The stories are set in the fictional American town of Midston. The plots feature characters who are interested in science and mathematics. Abrashkin died in 1960, after publication of the fifth book. Williams, however, insisted on Abrashkin being given co-author credit on the subsequent ten books as well, since he had been instrumental in constructing the series. Ezra Jack Keats illustrated the first four novels in the series. Although the exact location of Midston is not given, the authors wrote that a famed American of colonial times visited the town, implying Midston is somewhere in the original 13 states. In the book Danny Dunn and the Heat Ray, reference is made to US Route 1 and US Route 2 being located near Midston, and those roads meet only at Houlton, Maine.
Main character
Dunn is a boy, a fifth-grader when the series starts, although the school year ends at the end of the first book. He is looking forward to a career in science. According to book reviewer Andrew Frederick, Dunn is precocious and headstrong—a redhead whose adventures mainly include getting into and out of trouble.
Other characters
Professor Euclid Bullfinch, a researcher at Midston University. The Professor is also a musician who plays the bass viol. He is plump and somewhat bald, and smokes a pipe in some of the books. Danny considers him a mentor, and Danny's complicated problems often revolve around inventions by Bullfinch.
Mrs. Dunn, Danny's widowed mother, housekeeper for Professor Bullfinch.
Fellow classmate Irene Miller, Danny's friend and next-door neighbor. Irene's father teaches astronomy at Midston University. Irene made her first appearance in the third book and is particularly interested in physics.
Fellow classmate Joe Pearson, Danny's friend. Joe is the poet of the group, and he often functions as an amusing sidekick to Danny, expressing bafflement at the complicated technology employed by Danny and the Professor.
Fellow classmate Eddie Phillips, rival of Danny and a school bully.
Doctor A.J. Grimes, a friend of Professor Bullfinch introduced in the first book, Danny Dunn and the Anti-Gravity Paint. Grimes is a curmudgeonly figure, rarely taking the teenagers seriously, and often trying to antagonize the Professor. Doctor Grimes is also a musician who plays the piccolo; he and Professor Bullfinch occasionally play duets. Tall and lanky, he is in many ways a contrast to his friend Bullfinch.
of Galaxy Science Fiction said in 1961 that "Danny's adventures are always based on a solid science foundation, once the authors' usually wild main premise is digested".
