ABANDONED. Boy and Girl's adoptees die and move in with older couple, start finding keys to find a final treasure

[Josh]

I was with my friend at the library ad she mentioned a book she found once in her old moddle school library. She said that it was a mystery book about two children (boy and girl) whose adoptees die and they move in with an older couple. Throughout their time there they begin to find keys to different secrets around the area and theu continue to do this until they find the final treasure. My friend seemed to recall the book having purple flames running up the side of the book and i believe she mentioned something about a skeleton jester on the front cover though im not certain on that.

[Kristina]

Sounds similar to The 39 Clues. The first book has skulls on it.

[Josh]

I thought that as well but I had asked her about it and she said that wasn't the book

[Lobstergirl, au gratin]

Well that was fast - Josh left the group. Moving to Abandoned.