1897. Identical twins Harriet and Mae have always struggled to see eye-to-eye, but when one sister's envy of the other results in a shocking betrayal, she realises the only way she can make amends is by making the ultimate sacrifice. But that sacrifice has repercussions throughout the generations - and when in 1941 Ivy arrives in Singapore, posted there with the Women's Royal Naval Service, wanting to learn more about the period in her family's history that no one appears to know about, she isn't fully prepared for what she uncovers.