Jordan and Dan continue working through the 'books' within the Psalms. This time they look at books three, four and five and find that they can be seen to follow a spiritual journey.  They find that some Psalms express doubts and uncertainties and deeply question what God is doing. But by remembering what God has done in the past the Psalmist is led back to peace of mind and trust in God, ending with a call for "everything that has breath to praise the LORD"!