This profound and imaginative book effectively explores what we may expect to happen when we pray that ancient prayer, ‘Come, Holy Spirit’. After all, as the book concludes, “Christian faith is praying in the Spirit (Ephesians 6.18), worship in the Spirit (Philippians 3.3), and discerning the Spirit (1 Corinthians 2.15). It is none other than life in the Spirit (1 Peter 4.6).” I think this is a book to help us with that living. It puts forward an unmistakably Trinitarian pneumatology. Tomlin keeps repeating the distinctive role of the Holy Spirit in the Trinity. It is “to reach out from the very centre of the love between the Father and the Son” to “draw us into an experience of that love”, transforming life in all its dimensions and giving us “a new sense of self and purpose for living”. Given Graham Tomlin’s close association with Holy Trinity Church, Brompton, it’s not surprising that he refers a lot, in the chapter on the Holy Spirit and Evangelism, to the well-known Alpha courses, which originated at HTB. Helpful chapters continue on the Spirit’s activity in the world (focusing on the 4 arenas of Work, Family, Community and Environment), and on the kind of Church needed to engage with God’s mission to God’s world (marked by unity, holiness, catholicity and apostolicity). I found this a stimulating book both on the Spirit and on that ultimate mystery, the Trinity.