Moonlight follows Mick St. John, an immortal vampire and private investigator and his struggle to exist after he was bitten 60 years ago by his vampire bride on their wedding night. It also follows his internal torment as he falls in love with one he should not, one who is mortal named Beth, a news reporter, as well as his dealings with the woman who made him a vampire, his sire Coraline.
A string of vampire-like murders have been hitting L.A. It's up to Mick St. John to find out who's behind these murders, and while he's on the case he meets a woman from his past.
Our vampire PI begins to fear something worse then a stake through the heart when he learns a convicted murderer with some confidential information is being released from prison. It seems the killer is threatening to reveal Mick's undead identity.
You'd think that Beth would run for the hills now that she knows the truth about Mick's secret identity. Instead she decides to help the undead PI locate and stop a newbie vampire who can't control his bloodthirst. Mick hunts a renegade vampire who can't control his urges to kill.
Mick has got himself injured in a process of finding a young girl who is supposedly hiding in the desert. Due to scorching sunlight and immense heat, Mick is depleted of his vampiric ability to heal himself. As a result, Beth will have to take drastic measures to save Mick's life.
Mick hunts a teenage vampire who is hunting female escorts he finds on the Internet. Meanwhile, Mick and Beth try to avoid each other after sharing an intimate moment.
Mick finds himself working with Beth again to hunt a vampire linked to Josef's past and to the drug overdose Beth is investigating.
Mick experiences deja vu when a fire investigation that destroys a historic Hollywood hotel seemingly replicates the night Coraline died. Mick's sense of nostalgia grows when a woman he is working with bares a striking resemblance to his ex-wife.
When a cult target a young woman based on their belief that she was responsible for their leader's death, Mick offers to help her.
Beth gets jealous when Mick works on a case with a female photographer who bears a striking resemblance to his ex-wife. Beth then researches the woman's past and discovers the mystery lady isn't who she claims to be.
Mick arrives at Josef’s office building, which is on fire. Nothing is left intact. No survivors. Someone who knew Josef was a vampire attacked him with one of the two known ways to kill a vampire. Mick and Tom, Josef’s head of security, launch in investigation into the attack. Beth does her own investigating and interviews several people from Josef’s past, none of whom have anything nice to say. The twin investigations lead Mick and Beth to New York, and yet another surprise from Josef’s past.
Josh is working on the biggest case of his career, a conviction against a member of the MS-13 gang, possibly the most dangerous gang in the world. In an attempt to force Josh to drop the case, the gang threatens Beth, but Josh refuses to fold and enlists Mick’s help in protecting her. Unfortunately, Josh is left unguarded and is kidnapped with devastating results. Beth discovers an unwanted blood connection.
While putting Josh's affairs in order, Beth discovers evidence leading her to believe Josh was cheating on her. When she investigates, however, Beth learns that Josh was about to propose to her and that the woman she thought he was cheating with was actually a consultant he hired for a confidential case - a case that turns out to involve Mick. Coraline's disappearance from the hospital, with the assistance of an old friend, leads Mick to the discovery of a temporary 'cure' for vampirism and a surprising link to the French revolution. Meanwhile, a startling family connection of Coraline's is revealed.
Benjamin Talbot, a new A.D.A., investigates the murder of Beth's boss Maureen. Beth and Mick pursue their own investigation, Benjamin warns them not to spoil any evidence that could lead to the culprit. Mick provides some good advice and some surprising empathy to a troubled teenager Bonnie with secrets of her own.
Mick is hired to help protect a rising Hollywood starlet who feels threatened by paparazzi, but she ends up murdered. Meanwhile, Beth gets a new boss at BuzzWire.
The grandson of a WWII buddy of Mick's is kidnapped, causing Beth to learn more about Mick's hidden past.
A human is killed by a vampire in the heat of passion, causing Mick and Beth to face the ultimate consequences of a vampire-human relationship. The investigation of the murder puts Mick and Josef's secret identities in jeopardy, forcing them to join forces with the other vampires in Los Angeles to keep their secret safe.