Maybe 2 years back I remember having seen an episode of a US or Canadian Crime series where LEOs search a suspect’s apartment (someone suspected of selling Top Secret information to whichever foreign power) . This suspect’s (a female) flat seemed ‘clean’, no evidence of her being the spy/mole but the officers were surprised to find a multiple packs of playing cards around the flat.
Of course the discovery of those decks of cards allowed the ‘star’ of the show to figure out how the suspect was copying secret documents out of a ‘locked room’ with no electronic devices or paper. She was of course a mnemonist and memorising entire formulas or code.
I have googled til I’m blue in the face but I can’t find any mention of it online and I can’t recall which program it was. Doesn’t appear to have been Blacklist, Scorpion, Blindspot, Cyber CSI -I say ‘appear’ because the Wiki episode synopsis tends to be somewhat brief.
Anyone remember it?