The ambiguous teaser shows Kai wandering around the streets of London, looking for a clue. In the end, the idol is seen vanishing into thin air before a bird is seen flapping its wings behind the word, "EXODUS."
A special twitter account that is seen in the teaser video has also been setup here: @pathcodeexo. In addition, a special EXO website has been setup here where you have to input the correct password to proceed. This is all so mysterious! The pathcode is 10 and inputting the correct password leads to Kai's teaser images.