After you beat konquest go to earthrealm and locate the spirit liu kang train with him and then go to edina, once there go to G-8 and wait till Friday 12:00 AM and the tresure chest will be behind the tent

You might have to do the Rain mission first Rain is purple nija in edina talk to him and he is looking for a hideout. Go back to G-8 and you should find Jade there talk to her and go find Rain again. Speak to Rain and he should run off looking for the hide out. After that go back to G-8 and you should see Jade standing over Rains body and after that the mission is over