The Long Low Whistle (Killer VHS Series, #7)

The sound of the whistle that split Patricia's life in two still haunts her two decades later, its echoes leaving their indelible stamp on everything she does. The rift caused by her father's unsolved death haunts her, pushing her to ever more dangerous attempts to put his memory to rest. Breaking into mausoleums in the dead of night isn't how she pictured her life, but she'll do almost anything to know what happened.
When a group of amateur cryptid hunters shows up in her small town, Trish doesn't hesitate to take what might be her only chance to find answers, even if they're searching in the last place she should be. A sealed, abandoned mine; tight underground passages filled with unseen creatures, and impenetrable darkness await the crew, but it's the only path forward, and Trish won't leave her father's legacy buried, delving ever deeper into danger to where that whistle still moans.