Floodgates

An immortal who might finally have met his match.
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Merry Lytton, known as Merlin in ages past, is now a spy in the organization Potestas. Their mission is to gain unimaginable powers, and their charismatic leader has welcomed Merry but keeps a close eye on him.

Merry discovers that Potestas must recover King Arthur's lost grail to complete their nefarious plans. Unfortunately, it's connected to the seafloor by magical means. He fears for his sanity when bodiless voices start taking over his mind. Against voices in his head and hostile spirits in the sea, can Merry stop Potestas before they unwittingly trigger a tsunami of epic proportions?