What Lies Between Us by John Marrs is a dark psychological thriller that explores the twisted and toxic relationship between a mother and daughter living under the same roof. Maggie and Nina are trapped in a house full of secrets, resentment, and carefully controlled routines. As the story unfolds in alternating timelines, the reader slowly discovers the shocking events that led to their current situation, revealing betrayal, obsession, and horrifying acts committed in the name of love and control. The novel masterfully builds tension by blurring the lines between victim and villain, forcing the reader to constantly reassess who is truly dangerous and what lies they are both hiding.