Weeks have passed since Nell Batista and her friends from the Last Chance Club learned how to use magic to access the hidden world of New York City called the Nigh. Weeks since Nell found her missing brother River in the Nigh and was forced to leave him behind. Desperate to find him again, Nell is eager to improve her spell work and get back to the Nigh. Then a visitor shows up at the club with the news that Nell and her friends are all being fast-tracked to become Watchers, magic practitioners tasked with making sure important events unfold the way they are supposed to.

Before they can become Watchers, they must all pass three Initiation Trials, armed with tiny powerful creatures from the Nigh called Fates. Nell's Fates aren't particularly special, but they'll have to do, for the costs of failing are steep: not only would she be kicked out of the club and expelled from school, but she would lose all memories of magic--including the Nigh and her brother.

Then she gets word that the terrifying Minister is gathering her Magicians in the Nigh to come after both Nell and River. If there were ever a time for Nell to excel at her spell work, it's now...but can she master her lessons--and muster enough magic--in time?