A gameplay segment in which the player is tasked with following an NPC to a designated area, either on foot or in a vehicle. However, there's a special provision: for one reason or another, your target can not be alerted to your presence, as this will cause him to panic and flee, resulting in mission failure. Some games provide a "suspicion meter" that reveals how close the target is from getting spooked, and which can be reduced if the player further distances himself. See also Escort Mission, which may also involve tailing an NPC but for different reasons.