Supermodel Lula Landry falls to her death from a Mayfair balcony. The police conclude that she committed suicide.
Strike tells the police that the circumstances of Rochelle's death merit further investigation but is dismissed. He seeks out Lula's friends, the fashion designer Guy Somandeacute; and model Ciara Porter, and learns that Lula was looking for her biological family.
Robin gets key information from a salesgirl at the boutique Lula visited. Strike arrives just as Robin tries on a stunning green dress and he awkwardly averts his eyes as he explains his CCTV breakthrough - that a man left Lula's wearing a Guy Somé hoodie.
Strike is approached by Leonora Quine with a plea to locate her husband, the notorious writer Owen Quine, who has disappeared without a trace.
Delving deeper into the hidden meanings and concealed secrets of Bombyx Mori, Strike and Robin scour all corners of London's literary world to unmask the hugger.
Robin arrives at the office to accept a package from a courier in a rush.
When she opens it she is horrified to discover a severed leg inside.
Strike begins to pull together a list of potential suspects from his past, all of whom have vendettas against him. One of the names, Jeff Whittaker, relates directly to Strike's dead mother Leda. He brings in Shanker to help him, while Robin begins to research all three suspects.
Strike and Robin's close working relationship begins to rile Robin's fiancé Matthew, and the couple descend into rows. Adding pressure to the relationship, the investigation takes Robin away to Barrow-in-Furness with Strike overnight.
Cormoran Strike and Robin Ellacott are at odds following Robin's wedding to Matthew, but there's no time to mull on the new distance within their professional relationship, as a frightening visit from a potential client puts a new case on the table - and Robin and Strike set to work looking into reports of a strangled child.
Strike and Robin's startling discovery seems to confirm the story of the strangled child - but they're forced to leave the scene before they can properly investigate. Fearing their witness is in danger, they redouble their efforts to find him. As Robin deals with frustrations in her marriage and Strike accepts a dependency on a new girlfriend, their investigation deepens. The duo are taken all over London in pursuit of the truth, from a derelict warehouse filled with protestors to a high-society charity fundraiser. But ultimately, our favourite detectives are unable to stop another tragedy...