Where is the mail order bride?

Summer 2019 in New Zealand. On the last day of a backpacking holiday, Kate loses her bag on a vineyard tour and misses her flight home to England. An eccentric elderly man comes to her rescue and invites her to stay on as his paid companion in his country home, called Cardamine after the flowers around the pond in the garden. His wife is away, said to be visiting her home country, but Kate comes to suspect that her absence has a more sinister explanation. The idyll of sunshine, swimming, wine, and budding romance becomes overshadowed by mystery and fear and rumours of a coming pandemic.