Dead (Le Shadowhunter Fanfic)

Alison had been a Shadowhunter her whole life. All fifteen years. All her friends were Shadowhunters, and she had a parabatai. A good life.
That life was cut short when Ally was killed on a mission. Her friends were not surprised; many Nephilim didn't live long- but they were still struck with grief.
What did catch them by surprise is when the girl comes back to life, with no memory of being a Shadowhunter or being killed.
Who brought Ally back? Will her memories and training ever be restored?