It is summertime in Camp Half-Blood, and the Second Titan War is over. Kronos in vanquished, and there is finally peace. Then, one day, Grover and Thalia come into camp, supporting an unconscious demigod. They claim that they tracked and followed her from New England. And that she has a secret that could start an all-out war between the Olympians.

Ten years before Unwind, in a state far away from Connor, Lev, and Risa, a boy named Harlan 'Humphrey' Dunfee was sent to a Harvest Camp to be Unwound.