Fast-forward to the construction of the A82 in the early 1930s. According to Calum and my own unpublished theories, dynamiting the basin had collapsed an underground river that served as a North Sea access way, trapping a few of the creatures within Loch Ness. Both Alban and Calum confirmed Nessie was the last of her kind in the Loch. Calum said he and his late wife fed the beast during winters. That made sense, since the fish population of Loch Ness in winter would not be enough to sustain such a large predator. Of course, it was also possible that the beast had adapted to Loch Ness winters by hibernating.

Since Loch Ness was not teeming with 60-foot creatures, the animal my father had called a Guivre was most likely a mutant. Under normal conditions, mutations can occur in one of every 100,000 creatures. Beta-blockers in the eel's bloodstream would decrease the animal's sex drive. If the Guivre was a mutant, it was most likely sterile, explaining why there was not a breeding population of its kind in the Loch.

Whatever Nessie was, she obviously preferred to inhabit the Loch's deepest waters—

—until last winter.

Somewhere in the Great Glen, oil was leaking, and it was finding its way into Loch Ness. Though still undiscovered by the water bailiff and Scotland's EPA, it had nevertheless altered an entire season's migration of fish. Since the spawning fish could only enter Loch Ness from the River Ness, that meant the oil was most likely deterring them before they reached the Bona Narrows.

The oil had also altered the disposition of the eel population and the Loch's last Guivre. The Black Knights were patrolling the shorelines at night, trying to keep the tourists safe from the agitated Anguilla—and Nessie? Was that their mission?

No, it had to be more than that.

Last winter, as a precaution, Calum Forrest had reinforced his croft's fencing and installed underwater lights, along with…

Stop!

I stared at the computer screen, reworking the last assumption in my head.

Yes, Calum's lights were designed to scare off the creature, but that fence was still kindling to something as huge as Nessie. I had assumed the fence had been reinforced, but maybe… maybe it was just newer than the rest of the perimeter.

Maybe Calum had been forced to replace the rear fence last winter after the creature had attacked his herd of sheep?

But Calum was filled with rage. He not only wanted to keep Nessie away, he wanted it dead.

"My wife, God rest her soul, often had tae feed it for me."

His wife? Had the monster killed his wife?

A shiver ran down my spine as I typed out: Investigate Mrs. Forrest's cause of death.

Calum could have killed Nessie himself. He could have poisoned one of the sheep offerings, or lured the beast in close to shoot it, but he hadn't. The oath of the Black Knights had kept him from seeking revenge.