When three young students are brutally murdered in a Nigerian university town, their killings - and their killers - are caught on social media. The world knows who murdered them; what no one knows is why.

As the legal trial begins, investigative psychologist Philip Taiwo is contacted by the father of one of the boys, desperate for some answers to his son's murder. But Philip is an expert in crowd behaviour and violence, not a detective, and after travelling to the sleepy town that bore witness to the horror, he soon feels dramatically out of his depth.