The Smoking Mirror (David Bowles)

Summary: Carol and Johnny Garza are 12-year-old twins whose lives in a small Texas town are forever changed by their mother's unexplained disappearance.  Shipped off to relatives in Mexico by their grieving father, the twins soon learn that their mother is a nagual, a shapeshifter, and that they have inherited her powers.  In order to rescue her, they will have to descend into the Aztec underworld and face the dangers that await them.  (from amazon.com)

Where can I find it?: Boston Public Library: Connolly, Egleston Square, and South End branches, or as an ebook at https://bpl.bibliocommons.com/v2/record/S981C12008084

Tags: Twins; Texas; Mexico; Shapeshifting; Magic; Adventure stories; Aztec mythology in literature; Aztecs--antiquities