Wisdom's Way / Who killed William Naylor?

A local parking warden William Naylor, does not return home from work, and his family are distraught with worry. His wife Fiona, works part-time at the local zoo, where body parts are discovered in an enclosure. How did they get there and could they be the remains of her husband? Events are complicated by the sudden death of the deputy lion keeper. Coincidence or murder? Where do 'Daniel' and 'Leo' come in?