When the high-profile climate activist Marcus Calderwood is left for dead in a violent hit and run, he uses his dying moments to identify his killer - a serving policeman. But who is this unnamed ‘Officer X’? What does his own history reveal about the nature of trauma and revenge, and was Marcus’s death a careless accident or cold-blooded murder?

• Adeel Akhtar
• Nathalie Armin
• Michael Socha
• Joe Dempsie
• Fisayo Akinade