SABIRA, a girl of fourteen ascends a mountain in order to bond with a Frostsliver, a piece of the magical Glacier that flows from high on its slopes. She has been recommended for the honour by TSERAH, who accompanies Sabira with her packman, MIHNIR. Sabira feels guilt for her brother, prevented by an injury from being chosen for a Frostsliver years before. He later disappeared on the mountain, and Sabira feels that she could have prevented it.
Travelling the last distance to the Glacier alone, Sabira cuts free the cylinder of ice that would become her Frostsliver. Almost immediately, her triumph is dashed by an oncoming avalanche, caused by a mysterious explosion. Her Frostsliver is absorbed back into the Glacier after Sabira drops it in a mad dash to survive.
Narrowly escaping death, Sabira returns to the others and discovers that Tserah is dying and Mihnir is badly wounded. In order to save the Frostsliver bonded to Tserah, Sabira is forced to transfer the bond to herself. Tserah dies and Sabira is left to deal with both a new consciousness residing in her head and the creature’s strange shape changing powers.
With the path they had climbed up destroyed by the avalanche, the only chance of getting help for Mihnir is for Sabira to reach the source of the Glacier, following it back through the mountain to its base. Sabira climbs the mountain, pushing through the threats it throws at her with the Frostsliver’s help. One night she encounters a yeti, which she hides from.
Sabira makes her way into the caverns and tunnels inside the mountain, and finds that the yeti are in there too. She also discovers the cause of the avalanche that trapped her on the mountain - soldiers from neighbouring Ignata, under the command of the villainous Colonel YUPIN, a man whose bigotry Sabira knows first-hand having encountered him years before.
His plan is to occupy Sabira’s home city with a surprise attack from inside the mountain. With the help of a rebel from Yupin’s army, DANLIN, Sabira discovers the identity of the yeti – people who attempted and failed to bond Frostslivers. Sabira finds that her brother is one of them and uses their connection to convince the other yeti to help her defeat the army.
With the yeti at her side, Sabira battles the conscript army. The yeti that was her brother gives his life to protect her, and the Frostsliver is grievously wounded. Sabira manages to kill Yupin, and returns the Frostsliver to the Glacier to save it at the cost of her life.
Sabira finds to her surprise that the Frostsliver she cut at the beginning is still watching over her, and can take the place of Tserah’s, saving Sabira. With newfound power, she finds the Ignatian powder reserves and with help from Danlin detonates it, bringing down the caverns. Barely surviving the blast, she finds that the explosion has opened a way out of the mountain.
Sometime later, when she has had time to heal, we learn that by using Sabira’s information Mihnir was rescued from the mountaintop, though with terrible injuries from exposure. Sabira, now with her family and Danlin at her side, plans to find a way to heal the rift between her people and the Ignatians, intending to make it her life’s work.
