The setting is a remote mountain lodge where Dr. Polyantha Vashti Cassandra (Cassie), a world-famous anthropologist, has come to recover from a back injury. Confined to a wheelchair, Cassie is to be looked after by Grace Hollis, a fellow teacher and lifelong friend, with Grace's nephew, David, stopping by each week or so to deliver supplies and bring them news of the outside world. After David has departed the two ladies are surprised by the sudden appearance of three teenage girls, who claim to be students from a nearby college who have lost their way on a hiking trip. Hospitable at first, Grace and Cassie soon sense their visitors are not what they purport to be, and when they come across a newspaper clipping which reports a Charles Manson-like ritual slaying in a neighboring town they are shocked into awareness that their guests are the killers, for whom a statewide search is now in progress. When the girls realize that their identities are known they take their hostesses prisoner and the long night of terror begins, with Cassie and Grace using all their wits to stay alive and bring their tormentors to justice—a hope which seems to be perilously in vain until an unexpected turn of events sets things right in the final, surprising moments of the play.
A change of pace for this renowned author of comedies, the present play is a spinetingling thriller which pits two strong-willed spinsters against a trio of cold-hearted, bloodthirsty teenage girls—who have killed already, and are clearly ready to do so again.