Present day

For the last twenty years Shelly Summer has buried herself in her work at her veterinary clinic, trying not to think about her past. The only time she feels truly herself is when she's diving in the Mediterranean - the calm and stillness of the clear waters help her forget. Back home, Shelly stumbles across the belongings of her great-grandmother, Gertie Smith including a recording of Gertie's memoirs. As Shelly listens to it, she starts to uncover the secrets of Gertie's past, which might just hold the key to letting go of her own.

1916

When trainee nurse Gertie Smith signs up for the war effort, she is thrilled to learn that her destination will be Greece. With a head full of blue skies and handsome men, she boards the Titanic's sister ship, the ill-fated hospital ship Britannic. Unprepared for the horrors of war, she heads for the Greek island of Lemnos on a mission to rescue three thousand wounded British soldiers. But tragically, the Britannic never reaches its destination.

Gertie is sent to the Greek island of Kea, where she meets and falls in love with a Greek fisherman, Manno - but she finds herself torn between him and her duty to an English soldier. Gertie cannot shake the guilt she feels from that tragic night and is afraid her past will catch up with her.