WhenthedigitalnativeBenjaminturns18,heinheritsaboxofancientartefactsfromhismissingfather.HegivesanantiquebooktoSlien,thegirlhehashiseyeon,andunintentionallysetsachainreactioninmotion.AnoldmancalledZepposisalsoveryinterestedinthebookwhichoncebelongedtothecartographerMercator.UsingthesecretmessagesinMercator'sbook,thetriouncoversthemysterywhilehavingtostayonestepaheadofamysteriousrival.

人气女作家（恒松祐里）向恶名昭彰的私家侦探麦卡托（水泽林太郎）提出调查委托，称“自己可能正遭人追杀”。每天送达的神秘扑克牌仿佛预示着“杀人倒计时”，这究竟意味着什么……？麦卡托与他的助手兼作家美袋三条（须贺健太）的推理锋芒毕露——。