We first meet Elin as she is having an anxious episode inside of the funicular that she and Will are taking up the mountain, travelling to Le Sommet. Right away, mental illness becomes a prominent theme in the book. At the same time, the mental health struggles that characters in this book face are presented as reasons not to find them to be trustworthy, innocent, or even competent. Even as Elin struggles with PTSD following the death of her brother Sam and her own near-death experience at the hands of Mark Hayler, the insinuation that Laure might be suffering from depression causes Elin to suspect her of being involved in Adele’s death.

Elin fails to recognize that her own mental health struggle might also affect other people’s image of her. Will, her boyfriend, often doesn’t trust her judgement or finds her behavior to be unwarranted. He also becomes increasingly frustrated with her need to prove that she is capable of solving this case. She is also asked to stop investigating once the Valais police figure out that she’s on leave from her job as a detective back in England. Taking that extended leave of absence, even though it was for a valid reason, makes her seem unstable and incapable of investigating without problems or biases.