12 cards where the set is “mkm” and the collector number >= 324 and the collector number <= 335

Commercial District (Murders at Karlov Manor #324)
Elegant Parlor (Murders at Karlov Manor #325)
Hedge Maze (Murders at Karlov Manor #326)
Lush Portico (Murders at Karlov Manor #327)
Meticulous Archive (Murders at Karlov Manor #328)
Raucous Theater (Murders at Karlov Manor #329)
Shadowy Backstreet (Murders at Karlov Manor #330)
Thundering Falls (Murders at Karlov Manor #331)
Undercity Sewers (Murders at Karlov Manor #332)
Underground Mortuary (Murders at Karlov Manor #333)
Kellan, Inquisitive Prodigy // Tail the Suspect (Murders at Karlov Manor #334)
Kaya, Spirits' Justice (Murders at Karlov Manor #335)

The message was clear to Sorin—time to search for something else.