A businessman is murdered and Erica's sister was the last person to see him alive. Things get even more complex when Anna confesses that she spent the night with him. As the questions multiply and grow, it's discovered that Anna's common-law husband knew of the affair.

When looking for the subject of her next book, her agent suggests basing it on an event from Erica's own life. Looking back to her teenage years, she recalls the disappearance of her classmate, Peter. As she begins digging into the past, she sets off a chain of events that brings the mystery closer to home.

On a crystal clear, starry winter night a young woman dressed in a traditional Lucia gown is seen running across the ice. When she reaches an unfrozen channel, she drops her crown of candles in the snow and throws herself into the dark waters. As Erica investigates the case, she discovers the missing Lucia, a secret love affair and a man seeking revenge.

The coast guard finds two amateur divers dead after a storm and then discovers that two more are missing. Erica investigates something that could link all of the victims together: the divers had salvaged a shipwreck from the 1820s, where they found intact bottles of wine worth millions at auction.

When Erica finds photographer Stigge murdered in his studio, she can't help but take interest in the investigation. She learns that her mother-in-law, Kristina, was one among many in the neighborhood whom Stigge had blackmailed. With this news, Erica begins to dig even deeper into his past.