"The Bay" is a crime series that tells the story of Detective Sergeant Lisa Armstrong, who lives in Morecambe. She is a single mother raising two children and works for the West Lancashire Police Department. Lisa is assigned a case involving the mysterious disappearance of twins. When she goes to speak with their relatives, Armstrong discovers that she personally knows the twins' married stepfather. They had an affair on the very night the twins went missing. Lisa finds herself emotionally entangled in her own investigation.