Troll's Revenge — Cheryl Scott Norman

In this third novel in the Isshuayan Series, the troll, Goran, plots revenge by coercing two silversmiths to attempt the forbidden act of opening a path through the Shimmering to Ali's world. Ali's mother, Jane, is mistakenly kidnapped by the smiths and held prisoner in the Isshuayan tundra.

Ali knows she must return to Isshuay, but the Shimmering, the only way back, has become unstable and she almost loses her life in a failed attempt to make the crossing.

Both Ali and Jane are tested to their limits on different worlds. Aided by good friends, each must seek a solution to end Goran's malicious plans.