OST中的配乐变化多端，完美适应了全集复杂的情节发展。Inanearfuture,crimesandaccidentscanbepreventedbymakingjustonephonecalltothepast.However,thepeaceofthisutopianworldwillbedisruptedbyamethodicalkillerwhoseemstohavediscoveredtheonlyflawinthissystem.