The Darkest Eyes by Mick Brady

Will Roan is pretty sure she's losing her mind, but that's the least of her problems. What's worse is her growing anxiety that the disturbing things she's been seeing might be real. The aliens, for example. The nasty little bug-eyed monsters that have followed her around since she was a kid have been stepping up their harassment. Her mother is a little off balance, to be polite, and Will suspects she's veering down the same path. That's not good for a scientist. There's no room in her world view for magic or mystery. There's a rational explanation for everything, right? Lately, she's had too many experiences that defy reason, and they've put both her sanity and her career in jeopardy.

Will has run to the far corners of the Earth to avoid confronting the possibility that she's coming unhinged. She's extremely good at running. She runs from everything -- including love. Somehow, though, she's always brought back to the center of the madness. When her dying mother hands Will a beautifully carved crystal skull and urges her to use it to open a portal to Atlantis, her first instinct is to run as far away as she can get -- but the unnerving vision she sees in the crystal stops her in her tracks. Then something worse than psychosis happens, and there's no escaping its reality. Will's cherished nine-year-old niece disappears. In order to find her, Will has to abandon just about everything she once held as true about the world, starting with the belief that there's only one world to search.