It is Midsummer's Eve. Three young friends meet in a wood to act out an elaborate masque. But unknown to them, they are being watched. With a bullet each, all three are murdered. Soon afterwards, one of Inspector Wallander's colleagues is found murdered. Is this the same killer, and what could the connection be? In this investigation, Wallander is always, tantalisingly, One Step Behind.

Sweden's most tenacious detective races to unlock the twisted logic behind a madman's crimes. On Midsummer's Eve, three friends gather in a secluded meadow in Sweden. In the beautifully clear twilight, they don eighteenth-century costumes and begin a secret role-play. But an uninvited guest soon brings their performance to a gruesome conclusion. His approach is careful; his aim is perfect. Three bullets, three corpses. And his plans have only just begun to take shape.

Meanwhile, Inspector Kurt Wallander is just back from vacation. Constantly fatigued, he soon learns his health is at risk—but there's no time for rest when a fellow officer is murdered. Wallander soon discovers that the two grisly crimes are connected. A serial killer is on the loose, and the only lead is a photograph of a strange woman no one in Sweden seems to know. Forced to dig into the personal life of a trusted colleague, Wallander steps into a nightmare worse than any he could have imagined. Can he find his way out of the darkness before it's too late?