Here's how it works:
* The Red-Headed League: This fake organization is set up by the criminals to distract the target, Jabez Wilson, a pawnbroker. Wilson, being the only red-headed member of the League, is paid to spend his days copying out the Encyclopedia Britannica.
* Distraction: This seemingly harmless job effectively isolates Wilson, keeping him away from his shop during the day. The criminals know this is the perfect opportunity for their burglary.
* The Burglary: While Wilson is occupied with his "league" work, the criminals gain access to Wilson's shop. They intend to dig a tunnel underneath the shop floor, connecting to the bank vault next door.
* The Tunnel: The criminals choose to dig the tunnel during the day while Wilson is away, taking advantage of the fact that he's not around to notice anything unusual.
* The Red-Headed League is a Decoy: It serves as a way to ensure that Wilson wouldn't be suspicious of the activities happening beneath his shop, giving the criminals the time and space they need to execute their plan.
In essence, the "menial job" is a clever ploy by the criminals to keep their target distracted, allowing them to carry out their burglary uninterrupted.