The Alpha Nation — Kim Richardson

After a summer spent trying to prevent a catastrophic outbreak of illegal mystics, Zoey St. John starts her second year in the Operative program at the Agency.
But things don't stay quiet for long. Zoey soon discovers the global infrastructure that allows humans and mystics to coexist is under threat: the mirror-port matter transfers and borders which protect the Hives have been poisoned by a mysterious black oil, and the only safe haven for the Sevenths is on the verge of being overrun by evil mystics and Alphas.
To save the Hives, Zoey and her friends -- Tristan and Simon must infiltrate the Alpha City to find a cure for the black oil before the Hives are destroyed