This masterfully plotted ensemble novel opens one blustery evening past seven when a roadside tree suddenly topples onto housewife Mitsue Kayama and her baby stroller, critically injuring her two-year-old son, who dies after being rushed to the hospital. Mitsue's journalist husband, Satoshi, begins investigating what happened, partly at the urging of his boss, who pronounces the tragedy to be "manmade." What Satoshi discovers, however, is that his son's death is the outcome of a complicated web of events caused by the negligence of upwards of a dozen people. The police arrest a single suspect for involuntary manslaughter, a gardener who had skipped routine inspections of the tree. But the reason the man had been unable to check that one tree was because there was dog waste under it and he had contamination phobia. The waste in turn had been left behind by an old man who refused to clean up after his dog because of what he claimed was chronic lower back pain. And although a young city worker had been dispatched the day before the accident to clean up the mess when people complained, he too had left without doing his job after being teased by the neighborhood children. At the time of the accident, meanwhile, the ambulance had been delayed both coming and going, all on account of a traffic jam caused by a young woman who had left her large car blocking the road because trying to fit it into her home's parking space was too tricky for her. None of the offenders are willing to apologize for their part in the tragedy, which reminds Satoshi of a time not so long ago when he himself discarded trash where he wasn't supposed to at an expressway rest area during a vacation with his family. In the end the novel presents us all with thorny questions about morality and guilt.