Below you can find the In the sign of the four holmes refers to a seven-per-cent solution a concoction that includes this drug Jeopardy Words Answer. The answer to In the sign of the four holmes refers to a seven-per-cent solution a concoction that includes this drug has 7 letters. This clue belongs to the Sherlock holmes category and is part of Jeopardy Word Level 1478. If you scroll near the bottom you will find other clues and answers part of level 1478