Secret Button

Exploration Stage: Foggy Backstreet
From: Vera
Description: There's a tracker on Lucas's backpack, but its signal is gone. The tracker must've turned off due to his long stay in the fog. I'll try to activate it remotely. There's a special button inside my pencil. But where is it...? Help me find it!
Completed: Thanks for your help! I thought we wouldn't find my light bulb pencil. It's very convenient for making notes in the fog, as the light bulb illuminates the notebook. If you unscrew the light bulb, you'll find a button that activates Lucas's tracker. Shall we?