The story is set in Miami, a prosperous but dangerous city. On the surface it is a sunny and beach resort, but in fact there is an undercurrent of crime. The protagonist, Dexter Morgan, appears to be an excellent bloodstain analysis expert in the Miami Police Department and is deeply trusted by his colleagues. But he has an unknown dual personality, and his childhood trauma left him with a bloodthirsty desire hidden in his heart. After his adoptive father Harry found out, he taught him to direct this desire to those evildoers who escaped legal punishment, and formulated the "Harry Code" for him. From then on, Dexter acted as a secret judge in the dark.
