When Penny's mother is left a cottage in the heart of the country by a mysterious aunt, the family visit for a holiday. But within a short period, Penny finds herself called upon by the inhabitants of the garden in an extraordinary fight. As time passes, her brother is also drawn in and, after a journey of family betrayal and reconciliation, together they must face the final battle, the conclusion to a conflict that has been going on for millennia. The consequences of failure would be world-wide devastation.