Sally Miyake is a bold choice to narrate SUNNYSIDE PLAZA (Little, Brown, 208 pp., $16.99; ages 8 and up), Scott Simon’s debut as a middle-grade novelist. She’s funny, observant and perceptive. She’s also a 19-year-old with a developmental disability who lives in a group home where two residents have died unexpectedly. When police detectives recognize Sally’s capabilities and ask for her help investigating the deaths, she makes her first outside friends.

Some readers may question the choice to put a 19-year-old like Sally at the center of a novel for younger readers. Having a cognitive disability doesn’t make anyone an eternal child. But Sally’s pitch-perfect, brilliantly meandering voice reminded me that I first read (and adored) “Flowers for Algernon,” the story of an adult man with cognitive and developmental disabilities navigating similarly dark issues, when I was probably too young. Children are captivated by differences in others. In many ways, an overprotected young adult living in a group home faces the same challenges as a child testing the waters of independence. Can a fourth grader walk to school, or into a store, alone? Sally, like many of this book’s presumed readers, has never done these things.

Simon, best known as the host for NPR’s “Weekend Edition,” based the story on his experience working in a group home when he was in college in the 1970s. He remembers — with hilarious accuracy — how conversations with this crowd can boomerang between outrageous comments and remarks that poignantly hit a nail on its head. In fact, I wish he had set this story back in the time he remembers so well. As it is, there are unfortunate anachronisms.

Today’s children have been educated in classes alongside peers with every developmental disability under the sun, since it was mandated by law in 1990. Though Sally is bright enough to measure the world in mathematical equations (she tells us her age is “8 times 2 plus 3”), she has never attended school, never learned to read, never ventured too far outside the confines of Sunnyside Plaza, her group home. Most children have seen their peers with intellectual disabilities not just in the classroom but on a bus, at a sporting event, just walking up the street.