Alderson-Day (psychology, Durham Univ.) invites readers to join him as he investigates the experience of presence, the sensation that a phantom "other" has invaded one's thoughts or space. Drawing on first-person accounts, interviews, and research in various fields such as psychiatry, neuroscience, philosophy, and psychology, the author presents a robust investigation into the phenomenon. Readers will learn medical conditions such as mental illness, epilepsy, dementia, and stress can evoke a feeling of presence. Additionally, benign situations such as isolation, reading, and even sleep can evoke the experience. The author describes how individuals such as psychics may be able to conjure up a presence. While some may encounter a malevolent presence, readers may be comforted to learn that a visitation from an "other" frequently provides comfort or encouragement. No definitive theory is presented, however the author provides many avenues for further study. Readers looking for a compilation of eerie, supernatural stories involving presence may be disappointed. On the other hand, those interested in developing a richer understanding of the phenomenon will appreciate Alderson-Day's in-depth exploration of the topic and detailed endnotes. VERDICT Best suited for readers with an interest in psychology, parapsychology, and related fields.—Lydia Olszak