One day, during a break from cases, Sherlock Holmes receives a call from Greg Lestrade about a hold over investigation for a friend in America. Sherlock agrees, and the two along with Dr. John Watson are off to the States. Meanwhile, the Lyoko Warriors are getting strange signals, both to them personally and to the school's electronics. What could it mean? What is X.A.N.A's plan this time? And will the world's greatest detective find a mystery too big?