Sacred Ground's primary theme is the timeless one that evil motives and acts produce more evil, which must be stopped for the world to be set right again. This idea is worked out on both the mundane and the supernatural planes. Rod Calligan's greed leads him to build on an environmentally disastrous site. When his project falls apart he raids Indian graves and plants explosives. He plans to blame Native American activists for the damage and to collect insurance to recoup his losses. This leads to several deaths and to more violence as he tries to cover up his deeds.

But in raiding the graves he also disturbs the spirit of Watches-Over-The-Land, a great Medicine Chief of the last century. This brings onto the present scene the struggle of the Medicine Chief with his ancient, malevolent adversary, along with a flock of minor vengeful spirits called Little People. The evil medicine, thus freed, may target any vulnerable person who is around. Ultimately it kills Calligan's son Rod Jr. with a lightning charge through the television set, and Jennifer herself comes close to dying when she is thrown, unconscious, into a reservoir.

There is also a theme about the limits of our control of events. Calligan, the villain, has a fetish for total control — of his wife, his children, and his business affairs. He is even sure he can control press and police reaction to the disasters at his building site, by planting evidence that will be attributed to radicals and terrorists. Jennifer, in her other identity of Kestrel, is an apprentice shaman. Her grandfather, who is tutoring her in the medicine ways of all the Osage clans, cannot reveal to her what she lacks to become a full-fledged Medicine Woman. Jennifer is an over-achiever, and this carries over into her Kestrel role. She needs to learn to let go at a certain point, to stop following instructions and striving, and let the flow of the unseen world take over. Her ex-boyfriend David Spotted Horse also has to learn he cannot control his buddies or make events take the direction his ideology predicts. Once he sees this, he and Jennifer reconcile. Both are able to be more effective once they learn to tune into the currents of the spirit world. This is not a lesson in quiescence, but simply in not insisting upon imposing one's will and plans on the world.