From the publishers webpage:
They Shoot Wild Horses is a Shadowrun, Third Edition scenario that hints at the dangerous times that evolve out of the events in Year of the Comet.
The year is 2061. Halley’s Comet has returned to remind the myopic people of the Awakened world that there are things outside of what megacorporation makes the biggest profit. The media has proclaimed 2061 the Year of the Comet and sees the comet as a blessing – something to take peoples’ minds off of the sewer that is their daily lives. Others see the heavenly messenger as the harbinger of bad times. The end of all bad times.
But the comet isn’t the only event occurring in 2061; the year marks the 50th anniversary of the Awakening of magic. Shamans and magicians have seen their ranks swell with charlatans, con men, and hucksters duping both the mundane and the magical alike with “remedies,” trinkets and protection “pills” to ward off the next “awakening.”
This only obscures those who are really preparing for what the next stage of awakening might bring…