What's the difference between a bar of soap and the stuff we use to clean dishes, laundry and cars, and can you just use any of those in the shower? Adam tries to find out whether the stuff that's fit for baby ducks if good enough for you skin. Darren gives us a review of Determined: The Science of Life Without Free Will by Robert Sapolsky, which asks interesting questions about free will, whether we have it and what the implications are.