Duterte Harry: Fire and Fury in The Philippines. By Jonathan Miller.Scribe; 346 pages; £14.99. To be published in America as “Rodrigo Duterte” in September; $17.95.

AFTER Rodrigo Duterte won his first election in 1988—to become mayor of Davao, a city on the troubled southern island of Mindanao in the Philippines—the shadow of the Moon passed over his victory. The local word for an eclipse is also that for a fabulous, fanged sea-serpent: bakunawa. This dark omen epitomises the ghoulish detail in Jonathan Miller’s biography. It also captures the almost fantastical nature of Mr Duterte’s life. Since he became president in 2016, his monstrous tendencies have emerged in a brutal anti-drugs campaign, his treatment of critics and authoritarian rants. As Mr Miller, a TV journalist, poignantly shows, one of Asia’s oldest democracies and its 103m people are suffering—even if many seem to approve.

Mr Duterte presents himself as a straight-talking outsider among Manila’s elites. “Duterte Harry” portrays him as the tearaway son of the governor of the province of Davao, whose upbringing was unusual but privileged. One of five siblings, he skipped school, chased girls and hung around with paramilitary police who were supposed to guard him; Mr Miller thinks his foul language derives from those days. While his devoutly Catholic mother retained some control over him, his antics incurred a cruel punishment: kneeling on marbly mung beans with his arms outstretched. He went on to study law before turning his attention to his home town.

For 22 years Mr Duterte ran the city of Davao, apparently maintaining popularity ratings of 96% during that time. When he stood down, the local economy was growing at more than 9% per year. His tough stance on shabu (crystal meth), and against the criminal networks supplying it, later appealed to voters nationally. Mr Miller illuminates the darkness behind his boasts. More than 1,400 people are thought to have been murdered between 1998 and 2015 by vigilante killers known as the “Davao Death Squad”. Mayor Duterte spoke freely of criminals being “legitimate targets of assassination”, but denied responsibility. One of the book’s most compelling chapters relays a former killer’s account of the grisly tasks he says he performed.

Since becoming president, Mr Duterte has applied his methods on a bigger scale, at a cost of more than 12,000 lives so far, according to human-rights groups. In the country’s slums, arbitrary lists of supposed drug-users determine who will be shot to death. Notorious for his misogyny, Mr Duterte excoriates female critics with particular savagery. Senator Leila de Lima languishes in prison on trumped-up narcotics charges after daring to investigate his dealings with the Davao Death Squad. Maria Lourdes Sereno, formerly chief justice of the Supreme Court, was ousted from her post in May after she spoke up for judicial independence.

Yet Mr Duterte remains popular—in a presidency defined by contradictions. He jokes about rape but has enacted progressive sex-discrimination laws; he supports same-sex marriage and has pushed for greater access to contraception. He crusades against drugs but acknowledged using patches of fentanyl, a synthetic opioid, to relieve lingering pain from a motorbike accident (later he claimed he was joking).

Mr Miller’s conclusions echo a psychologist’s report written in 1998 as Mr Duterte’s marriage broke down. That described “a highly impulsive individual” who “has difficulty controlling his urges and emotions” and “seldom feels a sense of guilt or remorse”. “Duterte Harry” deftly guides readers through this warped political landscape to reveal the vulnerability of a tempestuous leader.