The Case of the Grey Assassin by Charlie Cochrane

Toby Bowe and Alasdair Hamilton make the perfect partnership onscreen and off. While hiding their relationship tests their acting skills to the utmost, a shared penchant for amateur detection challenges their intellect in a way that making films never can.
When a practical joker appears to be targeting Landseer Studios, they’re the obvious men to investigate the affair but life turns tricky when they also get asked to help a film critic who’s receiving threatening letters. Suddenly they’re involved with the hunt for a serial killer and the case begins to cut too close to home for comfort…