Prophets of Death and Madness - John Haas

The Necronomicon lies on the ocean floor, but there are other dangers, other hidden copies. In that loathsome tome lie ways to contact creatures as far above Cthulhu as Cthulhu is above human kind. Elder gods who could destroy all reality in the blink of an eye. 

Death lies in wait for Doctor Archibald Shaw, recent survivor of the Titanic sinking. Danger, both new and familiar, unseen and overt, conspire to drag him deeper into the dark secret world. Shaw finds himself struggling to resist an undeniable pull toward Arkham, Massachusetts and whatever new nightmare awaits there. 

Meanwhile Singh crosses the Atlantic in pursuit of his only friend, convinced he is already too late. What other option than to continue forward? He faces his own dangers in the ocean's depths, dangers which may prevent him from ever reaching Shaw. 

Separated for the first time in decades the two struggle against impossible odds, alone. Monsters. Nightmares. Strange portals. Elder gods. A strange new cult. 

Will Shaw and Singh reunite before death claims them all?