S5·E10 If a Body See a Body

On a day out with Mark, Ed finds a body in the park, but when Homicide arrives it has gone. Teased by his rival, Homicide Sergeant Larry Mullen, Ed is anxious to prove that there really was a body, but the Chief would rather have him working on a kidnapping case with the FBI. It soon appears, however, that the two cases may in fact be the same one.