You'll need to search the crate at the location shown in the map below while having the clue scroll in your inventory. Avoid bringing items that you are not prepared to lose. If you are attacked by another player you can teleport away unless you're above level 20 wilderness, at higher levels you have to log out before you are being attacked. At the far West side of the wilderness around level 13 there are green dragons and often also pkers. Your best bet for this step of your treasure trail is to go with just the clue scroll and a tele tablet, no other items. That way you keep the clue scroll if you die.

Required items: clue scroll, tele tablet.

Required quests: none.

Possible way of transport: Walk North-East from the chaos temple near Goblin village until you reach the mine, from there go North to the Dark warriors fortress.