Unexpected Lightning by Cass Sellars

For Sydney Hyatt and Parker Duncan, finding each other and falling in love wasn’t easy. All they want now is to build a life together, and things are just starting to head in that direction. But when they host a party for Parker's work colleagues, they unintentionally invite a dangerous stranger into their home. Obsessive letters of admiration escalate into promises of harm and threats of danger. Who is intent on harming them, and why? Sydney dedicates her every moment to finding answers, neglecting threats now aimed directly at her. When an unexpected twist places Syd at risk, Parker watches helplessly as she puts her life on the line once again. Will Sydney will be able to stop the threat before it’s too late?