“Fifteen years after the development of the Z1E Serum, the US intelligence agency SF7 still relies on the miracle drug as its ultimate surveillance tool: transforming its own agents into enemy operatives. Senior Agent Ryan Yang knows the serum better than most, having built his career on missions inside China. But after an assassination attempt in Washington, D.C., Ryan is asked to go deeper undercover than he ever has before. SF7 has restricted cross-gender use of the Z1E Serum for years, until Director Jade Spears authorizes an exception for an investigation too critical to lose.”