Trio of Sorcery by Mercedes Lackey

Collection of 3 stories. 

The first new Diana Tregarde story in almost 20 years and the first Jenny Talldeer tale in over 15 years.  Each story has a bit of a preface by Lackey to explain the time and place of the story.

Arcanum 101, which takes place in the 1970s, a young Diana Tregarde finds time between her studies at Harvard and her budding writing career to stop a supposed psychic from interfering in the police investigation of a kidnapping case. This was also more of a novella as it was over half the book in length.

Other books featuring Diana Tregarde 

Burning Water (1989)
Children of the Night (1990)
Jinx High (1991)

Drums, set in the 1990s, sends PI and Native American shaman Jennie Talldeer on a quest to prevent an angry Osage ghost from coming between Navajo Nathan Begay and his Chickasaw fiancee. 

Ghost in the Machine, set in the high-tech world of modern times, computer programmer and techno-shaman Ellen McBridge investigates a series of mysterious deaths linked to a multiplayer online role-playing game.

I was a huge fan of the Diana Tregarde novels so was really excited to pick this collection up.  Now I want to go back and re-read the rest of the books as well as look for the Jenny Talldeer books which I have not read.  Interestingly enough these stories were written in order of how much I liked it.  While I did enjoy the last story found it to be my least favorite maybe because  I'm not into online gaming.  I always enjoy these kind of books that Lackey wrote so am glad to see her writing in this style again.