Sherlock

The Sherlock Procedure

This trick uses the Mnemonica stack. A spectator freely selects and returns a card, then the deck gets two genuine riffle shuffles and a cut. You systematically eliminate cards in memorized order across three passes, identifying the selection either by finding it out of position in the final packet, or by noticing a gap (a missing number) during the passes.

Setup

Deck starts in Mnemonica order. Give a false shuffle, hand it to a spectator who goes to a far corner. They remove any card, remember it, replace it anywhere, then the deck gets two riffle shuffles and a cut.

The Three Passes

Hold the deck face-towards-you. Look at the face card and note its stack number — say it's #29. That's your starting point.

1. Pass 1: Upjog the face card (#29). Spread through the deck looking for #28. When you find it, upjog it. Then look for #27, and so on — always counting backwards. When you reach the end of the spread, strip out all upjogged cards. Remember where you stopped in the count (say #16).
2. Pass 2: Give a false shuffle. Continue from #15 (one below where you stopped). Same process through the remaining cards.
3. Pass 3: False shuffle. Continue counting down from where you left off.

Finding the Selection

There are two ways the selection reveals itself:

1. Gap detection: During a pass, if you're looking for #20 but encounter #19 first, then #20 is missing — that's the selection. Note it mentally and continue with #19.
2. Final packet: After three passes, roughly a quarter of the deck remains. These cards should be in memorized order with exactly one card out of sequence — that's the selection.

The Presentation

Frame each pass as eliminating cards the spectator would never choose. Glance at them as if reading their personality.

The Out

In rare cases, the selection ends up back in its original position — no gap detected and no out-of-place card. The deck is still in memorized order, so pivot to "Mnemonicosis" for a strong alternative finish.

Using This Trainer

Practice tab: Simulates the full trick with a realistic riffle shuffle. The face card appears at the bottom-right of the grid. Work up and to the left, clicking cards in descending stack order to upjog them. The "Looking for" display shows which stack number you should be seeking next. If you notice a gap during a pass, that's the selection.

Mnemonica tab: Full reference grid of the stack order.