In Odd Child Out, Gilly Macmillan follows a Somali family facing accusations as they become embroiled in a tangled web of betrayal. Facing the fallout from "a little anti-immigration demonstration" that took place in Bristol a week ago, DI Jim Clemo of the Criminal Investigations Department is asked by his boss, DCI Corinne Fraser, to investigate the case of 15-year-old Noah Sadler. Noah fell into the Feeder Canal behind Temple Meads Station. In his own voice, Noah tells us that he's in critical condition on the fourth floor of the children's hospital. Doctors have placed him in an induced coma, but Noah hears his parents anchoring him, telling him how he fell and banged his head while he was under the water.

For Clemo, the case seems to turn on Noah's best friend, Abdi Mahad. Abdi was at Ed Sadler's exhibition opening just before he met with Noah. Recognizing this case for what it is, at first Clemo attempts a gentle approach. Abdi, however, refuses to talk. According to his mother, Maryam, his father, Nur, and his 20-year-old sister, Sofi, Abdi is suffering from some kind of emotional trauma. He appears to be in shock, refusing to tell Clemo--or his family--what happened.

The scene plays on a relentless loop inside Noah's head: Abdi's pleadings; the drizzle; the dark canal; the black water, the surface "a thick, slick membrane" until he hit it. Noah recalls how the cold clenched his chest as he hit the water and the big sky "emptied over him." Alternating chapters drift between Noah, at the edge of consciousness, and DI Clemo, plagued by insomnia as he tries to get a handle on Abdi. Abdi looks much taller than Noah, but he's still very much a schoolboy. Clemo is anxious to investigate what went on at the canal, but Abdi seems afraid, as though he's seen something or done something that's terrified him into silence. Clemo's colleague, Detective Constable Woodley, has the feeling the boy is scared.

Macmillan deftly moves between Noah, Clem, and Sofia and her memories of the Hartisheik Refugee Camp where she and her parents lived in Somalia. Sofia's memory of the camp isn't perfect, yet she already knows from Abdi that Ed Sadler spent time at this camp. This link between their families thus feels much more real. Sofia shares with her parents her deep unease about Sadler's exhibition. It is Noah's situation, however, that threatens to complicate the case. He's not just any kid who's gone out for a lark; he's also a terminally ill teenager, the cancer automatically labelling him a victim. Realizing that sensitivity is paramount, Clemo sets about making sure that the authorities don't condemn his best friend without a fair examination of the evidence.

As the plot unfurls, of critical import is Clemo's connection to Abdi. When Abdi goes missing, the case threatens to come to a standstill. The nail in the coffin comes from local reporter Emma Zhang, who writes an inflammatory article stoking the embers of racial tension, which in turn puts Clemo under even more scrutiny. Abdi and Noah were best friends, "absolutely thick as thieves." Abdi was a godsend when Noah started secondary school. They're "nerdy boys" who go to chess competitions and study together. Meanwhile, word from the hospital is that Noah Sadler's condition remains stable and comfortable. Still, the fallout from the anti-immigrant march leads Fraser to demand that Clemo find the Somali boy: "he's got the answers, so it's time to stop pussyfooting around and put some pressure on him."

Displaying a great ear for natural dialogue, Macmillan unfolds a fast-paced plot in the Mahad family's emotional backstory, how their time at Hartisheik led to the subjugation of Maryam's terrible memories. When Abdi accidently discovers his mother's long-buried secret, his anger threatens to explode into a much harsher reality. Macmillan's descriptions of Bristol are gritty and authentic. While her scenes relating to Maryam and Nur in Hartisheik will devastate readers with a sensitive nature, the ultimate triumph of the main characters makes the exercise in trudging through human cruelty absolutely compelling.