Q&A with writer and Executive Producer Neil Cross, Executive Producer Kate Harwood and actors Russell Tovey, Bertie Carvel, Amrita Acharia and Nina Toussaint White. In The Sister, only Nathan (Tovey) and Bob (Bertie Carvel), an eccentric old acquaintance, know what really happened at that tragic party years ago…and they’ve resolved to keep it that way. But now, Bob appears at Nathan’s door with terrifying news that threatens to tear Nathan’s world apart.