This a story of a travel journalist Laura Blacklock. She is allocated an assignment of a lifetime to spend a week on a small cruise ship which she hopes will get her a promotion. This maiden voyage she boards is for wealthy investors. It’s a networking opportunity that could open a lot of doors for her. The story that follows is a mystery filled with suspense.
The narration brings out themes of gaslighting, depression, and anxiety. On the first night of the voyage, Blacklock realizes she had forgotten her mascara. She goes ahead to knock at cabin 10 which is occupied by a woman who assists her with mascara. Later at night, she’s woken by screams and a splash. She goes out to check and apparently sees someone slipping in the waters. She could also notice blood on the rails of the balcony. At cabin 10 the woman who had given her mascara is missing and cannot be traced. The mystery is that cabin 10 was never occupied as is confirmed from the records. The security never buys her story and instead manipulates her into doubting her memory.
Blacklock is going through depression. Just before the voyage, her apartment was broken into. She is anxious and has not been sleeping well since then. The antidepressants she is taking are used to justify why she cannot be trusted. Apparently, she cannot be trusted to differentiate reality and fantasy. When she sticks to her story Nilsson, the head of security thinks she is indeed crazy. She is threatened for causing trouble by propagating a false story. Any potential evidence is cleared. Blacklock never doubts her sanity. As the story unravels, it is shown she was right all along.
