GW2 No More Secrets is the last story achievement from Dragon Bash. In order to even reach this part, you need to complete all previous achievements like: Ceremony and Acrimony achievement, Hard Boiled, Every Piece Matters (all five suspects).
Talk with Inspector Ellen Kiel, near Lion’s Court, in Lions Arch, in order to get into The Scene of Crime instanced area. There you will be a witness of the final part of the story, you started with Ceremony and Acrimony. Upon reveling who is the true suspect and defeating couple of enemies talk with Investigator Ellen Kiel to receive No More Secrets Achievement and additional item called Marjory’s Journal. This unlimited usage item grants you ability to replay a scene from Ceremony and Acrimony achievement.