Here's a great place to start - Mike Reeves' new book The Good God: Enjoying Father, Son and Spirit. Here's what Terry Virgo thinks about it:

"Mike Reeves not only helps us grapple with a difficult doctrine but draws us to the magnetically attractive centre of all things. His light touch and theological wisdom combine to provide a truly helpful book which both clears your mind and warms your heart.”   

Tim Chester helps us stop thinking of the Trinity like our appendix (we know it's there but have no idea what it's for), and shows how in fact the Christian faith is Trinitarian through and through. 

In the first in a series of three talks, Mike Reeves argues that the trinity must not be an 'add on' to our general belief in God. Rather, that way of thinking is actually profoundly unChristian, leading to a view of God that is a universe away from the Triune God of love revealed in the Bible. 

In Delighting in the Trinity, Tim Chester sets out the Biblical case for the Trinity in a clear and easy to understand way. He looks at how our thinking about the Trinity developed historically (the division between East and West and how the two traditions were brought together in the Reformation). Chester finishes with practical implications of the Trinity - what it means for revelation, salvation, humanity, and mission. Recommended! 

Jonathan Edwards takes us deeper into the mystery of the Trinity. What does Jesus mean when he says that he is in the Father and the Father is in him? How is it that Jesus dwells in us, but so also does the Spirit? What does Paul actually mean when he says, 'For from him and through him and to him are all things'? The Word of God, says Edwards, exhibits many things concerning God's triune nature 'exceedingly more glorious and wonderful than have been taken notice of.' Spend some time with Edwards, and take notice of the deep things of God!  

If you want to go even deeper, take a look at our book recommendations for the Trinity and the doctrine of God - from Owen and Calvin to Gunton and Zizioulas.