In Racso and the Rats of NIMH, the Rats of NIMH have developed a self-sustaining community in Thorn Valley, where they are completely isolated from humanity. Timothy Frisby, the youngest son of Mrs. Frisby, travels from his family's home to Thorn Valley. (Although his mother is an ordinary mouse, Timothy has inherited the extremely high intellect and long lifespan of his father, NIMH escapee Jonathan.) During his trip, Timothy meets Racso, the son of Jenner (a rat of NIMH introduced in first book who is widely considered to be a traitor). Timothy and Racso arrive at Thorn Valley, but while Timothy integrates and begins receiving the same accelerated education as the rat children, Racso, coming from a colony of savage urban rats, has trouble adjusting to life in a cultured town of rodents. Racso is also burdened by his family history, as his father deserted the rats' previous colony, placing them in danger of extinction. Life in Thorn Valley is suddenly threatened when humans begin planning to build a dam there, flooding the entire area. Racso, Timothy, and the entire rat colony must observe and sabotage the dam construction before the valley is underwater.
A review from the University of Chicago's Center for Children's books states that, "Conly has completely mastered the bucolic tone of the first book", and that "Characterizations all around are more detailed than in O'Brien's book".
Connections to previous works
Mrs. Frisby and the Rats of NIMH
Racso and the Rats of NIMH is a direct sequel to the Newbery Medal-winning book Mrs. Frisby and the Rats of NIMH by Jane Leslie Conly's late father, Robert C. O'Brien. Conly wrote her sequel long after O'Brien's death in 1973, so even though Conly's book attempts to answer many of the open-ended questions posed by the original, it is still Conly's work and not O'Brien's. One of the most anticipated events of the first book was the possibility of Mrs. Frisby's children (Teresa, Martin, Timothy, and Cynthia) having grown up to visit the rats themselves and partake in adventures of their own. Within this book, however, only Timothy is shown as having actually left for Thorn Valley. Teresa and Cynthia are still at home, and Martin has started a family of his own. While it ties up this plot point cleanly, many readers criticized this, feeling that the other children had had much potential and deserved more exploration. Another answered question from the first book is the subject of Justin, one of the rats who was a major character in the original. In the end of the first story, it is hinted that Justin sacrificed himself when he went back to rescue a fallen rat. However, Conly chose to keep Justin alive and well in the second book.
Another subject in which more information was brought to light was that of Jenner. In the first book it was hinted that Jenner had died, but in an event prior to those of the book. Jenner had disagreed with Nicodemus over leaving the city, and took a group of separatists to start a new colony. In the end of the first book, it is revealed that NIMH had found a number of unusual rats dead, and it is assumed that this is Jenner's group.
However, Jenner, according to the sequel, had in fact managed to escape the fate of the others and start a family of his own. Although he and the few surviving separatists had malevolent feelings toward the Thorn Valley group, they kept their distance, still believing that their way of life was better. In the sequel, it is revealed that Jenner had started a family, which Racso happens to be a part of. Jenner later makes a surprise appearance in the story and shows that despite his questionable loyalties, he cares strongly for his son. Some readers feel that the inclusion of Jenner as a semi-villain and antihero was heavily influenced by the film adaptation of the first book, The Secret of NIMH, in which Jenner played a much more central role than he did in the book.
The Secret of NIMH
The book sequel seems to be subtly influenced by Don Bluth's film adaptation of the book, The Secret of NIMH. The most prominent of these influences is the inclusion and characterization of Jenner; however there are many others, including Jeremy's more whimsical personality and Mrs. Frisby's red cape. The most glaring difference between the book and film, however, is on the subject of Nicodemus: not only did he survive the first book, but was also considerably younger in it. There is also the Red Amulet, a story prop unique to the film.
Despite a few plot similarities Racso and the Rats of NIMH has absolutely no connection to The Secret of NIMH's sequel, The Secret of NIMH 2: Timmy to the Rescue.
- Conly, Jane Leslie; Lubin, Leonard; Conly, Jane; Lubin, Leonard B.; and O'Brien, Robert C. (1988). Racso and the Rats of NIMH (reprint ed.) HarperTrophy. ISBN 0-06-440245-2.