Hammer of the Gods by John Whitman

Loki, the trickster god of Norse legends, lies chained to a rock, tortured by the venomous fangs of a serpent as punishment for offending Thor. Alex enters the myth as Loki’s son, Vali, and refuses to let his “father” face such a horrible fate. But if he acts to rescue Loki, will he destroy the very fabric of the universe? His sister Cleo watches his adventures from the computer monitor and advises Alex when she can, but ultimately, the decision is his.

From the Trade Paperback edition.

cover variations