I'm currently reading RSVP to Murder by Carol Pouliot. This book is the fourth in the Blackwell and Watson Time-Travel Mystery series.
A chance to attend a holiday party at a great camp in the Adirondacks? In 1934? Yes, please! Olivia Watson is excited to join Detective Steven Blackwell, even as it will test her ability to remain in the past away from the house she and Steven share. It's a good thing that their host, publisher Gil Racine, has planned plenty festive activities, as a blizzard arrived along with the guests preventing anyone from leaving. A rousing round of carol singing is stopped abruptly as their host keels over...poisoned. With the blizzard preventing local police from arriving, it's up to Steven and Olivia to begin an investigation. The murderer has to be one of the family or staff, but who?