Therin will be double moving while sneaking, 80 feet a round (taking the -5 to hide and move silently) toward where the lighting came from.  Thankfully that spell does have a tendency toward pointing out where it came from... that will still leave her with a healthy +22 to hide and +18 to move silently, and with her hide in plain sight ability, she doesn't really have to take a roundabout route to her destination... hopefully with her +10's to spot and listen, she'll find the enemy spellcaster quickly... before he throws too many spells at the party from out of their effective range of retaliation.