Vengeance Over Vanaheim, book 3:

Samantha has faced incredible odds and climbed past the first two Realms of Valhalla Online in her quest to reach the final Realm - where she can learn the truth about how she came to be in Valhalla in the first place.

But now she is alone. Cut off from all support, Sam must struggle to win through this strange new world on her own. With the black archer still on her tail, Sam has to move quickly to win through Vanaheim before he can find a way to put an arrow into her and finish her quest for good. Because his arrows do not merely kill. They obliterate all traces of the code for any being they strike, wiping them from Valhalla forever.

But Samantha has a plan. If it works, she'll flush the archer out and finish him off, then win through the Realm and on to the next. If she fails, she'll cease to exist.

Hel Hath No Fury, book 4:

Trapped between two goddesses is the worst "rock and a hard place" Samantha has ever run into. Even worse, the "goddesses" are really advanced AIs - artificial intelligences. One of them is plotting to go all "Skynet" on the world, and it's up to Sam and her friends to put a stop to it.

Winning this battle isn't just about staying alive or solving a mystery. This time, everything is at stake. If Samantha fails, the outside world will burn, and everyone she ever knew or loved outside Valhalla will die.