A young historian named Cullen Cummings goes to Scotland on a search to find more about his family line. He meets a mysterious woman who leads him to a valley with a tomb. Cullen opens it and fears for his life after seeing something supernatural. He quickly returns home, but he brought something back with him. Cullen soon dies and the police try to piece together what was behind his death. A drunken fisherman named David Cummings leaves the pub and hears a woman crying out for help as she nearly drowns. He goes to her rescue but it is duped. She transforms into a banshee and tricks him into a pact marking him with a larva insect tattoo to summon and find him anywhere. He learns that he must bring her victims otherwise he dies. He meets a woman named Mora Danning who works as an outside temporary accountant for his job. They have an instant attraction to one another.
Cullen’s cousin, Emily quickly buries Cullen as a part of the Cummings tradition, but with a hidden motive. Mora and David become close fast and start a relationship. David and Mora continue to see one another despite him not telling her his secret. He continues to bring banshee more women, but David struggles daily with his morals and the town caving in from all the publicity it gets from the recent murders. Strange things begin to happen more so around the town as the mysteries begin to unravel a little more each day. Some people begin to wake up from a magical inheritance over the town. Few know of the truth behind the Cummings family. Some threaten to expose and others remain hidden with secrets that could benefit their own devices. David and Mora try to make plans to leave, but he knows he can’t. A detective named Higgins is hot on the trail to find who the murderer is. David’s mother, Emily finds out about David’s pact and destroys the evidence that could link her son to the crime scenes.
Mora stays by David and opts for them to leave. Emily becomes increasingly fearful of what could happen to her son. David tries to go on daily but each day gets harder with the banshee threatening him. More people disappear and the veil around the town begins to fade. The sliding line between fantasy and reality wave over the people and town. Many people begin to wake up to what their former form or life was before. The banshee manipulates David to find people for her even though he requests for her to end his life, but she doesn’t. He tries to tell Mora his real secret at the last moment and the banshee appears to come and kill Mora. He decides to not tell her in order to save her life. Mora and David leave for the cabin. Higgins finds a witness who links David to the murder scenes with evidence. Now it's against time for David to dissolve the mystery surround him or the shadows of the night would soon claim him and all he loves.