When the personality that lives in Fourmille's brain is amnesia, the investigation to release it becomes more complex! Many cases of amnesia appear in the population of EKHO. In New York, Juan, Mexican researcher for a US laboratory, has adapted the body of Fourmille. He discovered that his employers have spread a prion that makes amnesia, in order to better sell an antidote to their invention... To free Fourmille from this host, our friends go to Mexico City in search of the past of the deceased Juan..