A soft, metallic click breaks the silence of the room. An inconspicuous strip on the side of the old, dark wooden box comes loose, and with a gentle glide, the hidden compartment slides out.

On dark, slightly faded velvet lie three objects that haven’t seen daylight in decades:

First, there’s a heavy brass clock without a glass case. Its delicate gears turn in a silent, fluid rhythm, but the hands move backward—unstoppable and utterly unaffected by the laws of time.

Next to it lies a rolled-up parchment map, drawn with shimmering, copper-colored ink. It doesn’t show continents or seas, but rather the intricate network of long-forgotten tunnels and hiding places—directly beneath the streets of your own city. A small, deep red wax stamp is placed in one spot.

And finally, a wrought-iron key, surprisingly cool and heavy in the hand, its bit shaped like a triple spiral. A yellowed strip of paper is wrapped around its ring, bearing the words, in elegant handwriting: “Only fits the lock that can only be seen when the light goes out.”

Which of these three objects will you take out first to unlock its secret?