The police receive anonymous emails. Their author demands to find the killer of Hanneke Sloot, a young employee of a law firm, and claims that the police leadership knows the name of the killer. Until the culprit is brought to justice, he threatens to shoot police every day. After an unknown assailant makes good on his threat and shoots a young constable in the leg, Captain Benny Grissel of the Major Crimes Unit is assigned to investigate.