I Love You Goodbye. Honeybone, #5

Retired U. S. Marshal Dean Honeybone, his life-partner Jean-Luc, and their daughter Kaia have started a new life in Austin, TX. Jean-Luc has taken over a restaurant and has hired their neighbor, Manda-Jane Witten, as part of his kitchen staff. Dean, Jean-Luc, Kaia, and even their dog Michael have come to adore Manda-Jane and her husband, Parker. During violent storms that shake Texas, Dean learns that Manda-Jane is deathly afraid of water, and when the couple's home is flooded, Manda-Jane and Parker come to stay chez Honeybone, which serves to deepen the bond between the two families.
But when a mysterious cousin of Parker's namded Ronnie arrives to help the Wittens repair their home, Dean becomes suspicious of him, convinced the guy has done serious prison time. Though Ronnie soon returns to his home in Birmingham, strange things start happening over at the Witten home. And then the couple disappears. Dean becomes worried for their safety and teams up with an active U. S. Marshal to track them down.
Kaia, however, seems to think he's too late. She keeps saying they're gone and that Dean has to listen to the song "I Love You, Goodbye" to understand the reason why...