In Enfield, Hertfordshire, Alan Titchmarsh and his team transform a garden for Yvonne, a woman who has devoted her life to combatting knife crime after the death of her son who was tragically murdered when he was just 17-years-old. Alan's design is all about the garden becoming a healing space, where Yvonne can remember her son, and where the family can come together again. Elsewhere, Katie Rushworth learns just how healing nature can be at the Cascades Gardens in Derbyshire.