Kate Dickie, Kayvan Novak, Jo Hartley, and Gemma Whelan also star.
Tropes:
- Asshole Victim: Ruth thinks they're all assholes, but of the ones we see, only the guy in the bar, Dan, and Ella qualify. We're encouraged to think that Tom is this, but he reveals Hidden Depths when she comes to kill him.
- Connected All Along: Ruth appears to be randomly killing people. But it turns out these are all people who were on the climbing expedition where her partner died.
- Crusading Widow: Ruth is determined to get revenge on the people she holds responsible for her partner's death.
- Enemy Within: It's ambiguous, but heavily implied, that Ruth was only inventing her fetus's voice as an outlet for her own grief.
- Fetus Terrible: Ruth hears her unborn baby telling her to kill people. But the end, where Ruth sees her baby and realises she's "normal", makes it much more likely it was she was making it up.
- The Ghost: Although dead, Ruth's partner is never seen.
- Maybe Magic, Maybe Mundane: It's heavily implied that Ruth was hallucinating her fetus's voice, but it's never answered.
- The Needs of the Many: Discussed and invoked. Tom cut the cord on Ruth's boyfriend because otherwise he would pull them off the cliff and kill them all.
- Not Really a Birth Scene: Although not shown onscreen, Ruth's partner's death is described as being like this. He and his friends were out climbing, there was a mistake, and the weight was too heavy. The leader had to cut the cord to let him loose, killing him but saving all their lives. As part of her Roaring Rampage of Revenge, she stabs a couple of her male victims in the stomach in an inversion.
- Pregnancy Makes You Crazy: Very literally. Ruth hears her baby's voice from inside her womb — and she's also haunted by knowing that her partner was ambivalent about having a child.
- Tomato in the Mirror: Ruth appears to realize that it was her own homicidal urges, and not her baby's, that caused her rampage.
