linger by maggie stiefvater

Linger, the second book in the Wolves of Mercy Falls and sequel to Shiver, finds Sam surviving the winter on his own without his pack. Sam and Grace are inseparable. When the temperature warms, Cole and Victor shift from wolves to humans. Victor is unable to maintain either form leaving an unfeeling Cole, who wants desparately to escape the human world and remain a wolf forever, to wonder is there more to shifting than temperature. Sam, the leader of the pack in Beck’s absence, must find a way to keep everything under control especially as Grace’s fever continues to linger and her symptoms escalate.