Lost Time - Stuart Jaffe

In her short time with the Parallel Society, Roni Rider has faced many deadly creatures and horrifying situations. But nothing haunts her more than her Lost Time -- the large gaps in her memory stolen when she was a child. For Roni, it is a constant reminder the she is incomplete.
When a creature from deep within the Caverns reaches out to her, she is set upon a journey that will take her beyond anyplace she could imagine, a journey to find out what was stolen and why. She'll discover the truth behind her missing past, the dark secrets that had been kept from her for years, and the horrible repercussions of it all.
But first, she'll have to remember how she got there.