Trust worthy (Charlizabeth)

This AU they are both the same age.
Charlie and Elizabeth are in 9th grade at their local "Amuo Middle School" in England. (Made up name-) they are both British girls who don't know each other are dead (they drank a weird brownish black liquid that they thought was tea since it's very popular in England, and became visible to everyone) and to their surprise, they run into each other in the school halls, it reminds then of the past between them in just that Small moment. They have tragic lives that they lived through that they try to solve together. What happens next? Do they find out each other's deaths?