Those Giants

Erika Stannusson is a fresh arrival from the ninth century. With the help of friends Karl McGregor, and Adam 'Finch' Bird, she finds her way in the 21st-century city of Marshton. Before she arrives in Marshton however, Erika runs into Norse troublemaker Loki. Disguised as Chief Norse God, Odin, Loki gives her a small box containing Viking King Harald's blue tooth.
As a gift, it's ordinary until she shows it to Karl and Finch. Ignoring Erika's instructions not to, Finch opens the box. Erika undergoes a worrying change.
In the ninth century, Ulf the Viking receives an identical box from Hela, Queen of the Norse Underworld. Ulf is angry at Erika, Karl, and Finch, who cancelled his Vikings Rule celebration. He wants revenge.
Hela assures him revenge comes in small packages; a tiny box containing one of Ulf's fingernails, enchanted by her sorcery.
Fast forward to Marshton, where things aren't going well. On the surface, everything looks fine. But below the surface, not so much.
Asgard's Chief of Mischief, Loki, steals Thor's hammer and sets up shop in Marshton's sewer system. He wants to kick-start the final great battle between gods and giants-Norse Armageddon-Ragnarok.
Loki's plan needs help from the fire and ice giants. His daughter, Hela, is the only one who can summon them. But, father and daughter argued and haven't spoken to each other for 2000 years.
Loki uses Harald's tooth to control Erika. She morphs into an exact copy of Hela when she opens the box containing it. Loki welcomes the summoned giants.
Ice giants freeze the city's water. Fire giants light up anything that will burn. Scientists believe it's climate change. Marshton's emergency services have no answers.
Karl and Finch, meanwhile, are dealing with Erika's body morphing gig and the fact that the new school principal has lied to them. Lies pile up, and the boys discover Erika also has been lying.
With the truth dodging every which way, Finch suggests a fact-checking mission to Marshton Library. Books, he says, don't lie.
Ulf invades the library and kidnaps the boys. Their capture leaves Erika isolated. Erika, ninth-century girl of the forests, finds herself alone on the city streets of the twenty-first.
Those Giants is the second outing for Karl, Finch and Erika. It builds from the story begun in Those Vikings. Those Giants is a tale of friendship, dealing with problems, and the blurred lines between truth and lies. Suitable for readers aged 10-12 years.