Thorndike Press large print core series.

"In retreat from a devastating loss and crushing injustice, Katie lives alone in a fortresslike stone house on Jacob's Ladder island. Once a rising star in the art world, she finds refuge in her painting. The neighboring island of Ringrock houses a secret: a government research facility. And now two agents have arrived on Jacob's Ladder in search of someone--or something--they refuse to identify. Although an air of menace hangs over these men, an infinitely greater threat has arrived, one so strange even the island animals are in a state of high alarm. Katie soon finds herself in an epic and terrifying battle with a mysterious enemy. But Katie's not alone after all: a brave young girl appears out of the violent squall. As Katie and her companion struggle across a dark and eerie landscape, against them is an omnipresent terror that could bring about the end of the world" -- Page [4] of cover