The plot of Dead in the Water relies on the concepts of near-death experiences (NDEs), recovered memories, electroconvulsive therapy (ECT), and the impacts of hereditary illness on behavior. Although some aspects of these concepts are realistically portrayed in the novel, it relies heavily on speculative and highly fictionalized details of these medical concepts and treatments.

NDEs are psychological phenomena that occur at or near the moment of death. A small percentage of people who experience NDEs report seeing bright lights or having a feeling of calm. In common parlance, this is often referred to as “seeing your life flash before your eyes.” Dead in the Water takes this scientific reality and heavily fictionalizes it, creating a situation wherein the protagonist, Damon Lister, visualizes key moments of his life.

With every successive NDE, Damon’s memories become more detailed. This is representative of a phenomenon known as “recovered memories,” which refers to experiences, especially those experienced as a child or young person, that are so traumatic that the memory is suppressed and eventually recovered. The concept is highly controversial and disputed. Since memories are inherently highly unreliable, they can easily be implanted by well-meaning therapists or other authority figures. However, in Dead in the Water, recovered memories are portrayed as accurate and reliable. While Damon might not recall everything immediately due to his successive ECT treatments, what he does remember is proven to be largely accurate.

In Dead in the Water, ECT is highly fictionalized. It is a real medical treatment that involves the application of electrical impulses to the brain. In the United Kingdom, where the novel takes place, ECT is very occasionally used in the treatment of severe depression, treatment-resistant mania, and catatonia. In Dead in the Water, ECT is portrayed as a controversial and even illegal treatment that can erase and assist in the recall of memories and reduce criminal behavior. This portrayal of ECT is highly speculative, serving as a deus ex machina rather than as a realistic portrayal of this form of treatment.

Dead in the Water suggests that Damon’s extreme behavior is partly the result of a hereditary brain tumor or similar condition. This is shown in the parallels between Damon and his half-sister, Sally, who both experience nosebleeds and violent outbursts. The implication is that these brain tumors cause their behavior, but this is an entirely fictionalized medical condition. In reality, anti-social behavior and violence are not the result of damage to a localized part of the brain but arise from a combination of factors. It is exceedingly rare for brain tumors to be hereditary without any other accompanying pathologies like scoliosis or tinnitus. The brains of young children are highly plastic, meaning that damage to one portion of the brain, as from a tumor, can often be compensated by the growth of neurons in a different part of the brain. Overall, the treatment of brain tumors and their link to irrational behavior in Dead in the Water are highly fictionalized and should be seen as figurative rather than literal.

The combination of real medical technologies with fictional elements places Dead in the Water firmly in the realm of speculative fiction. Author John Marrs is best known for his work in this genre, such as his best-selling novel The One (2016) about people getting matched for life based on their DNA.