PLOT: time travel murder mystery

MC finds the journal of a girl from the 1920's. (She can maybe work at an antique shop... or find it in the attic of the house her family just moved into... or could be staying with a relative in a creepy old mansion, etc). She becomes obsessed with the girl in the journal and does some research. Finds out that the girl & her family were murdered way back when. She falls asleep one night in the midst of her research and when she wakes up she's in a totally different era. She's been somehow transported back in time and desperately tries to save the family before they're murdered.