1875. Terrified that her life is in danger in her abusive marriage, Emma flees to the safety of Nightingale Hall with her two children, seeking support from Squire Nicholson. A housemaid, overhearing a shocking revelation, persuades Emma to run away to London, before she is questioned and wrongly accused. The family's new life in an East End slum is a stark contrast to what they're used to, and Emma lives in constant fear of being discovered. A chance meeting with the infamous Captain Rufus O'Sullivan marks the beginning of a unique relationship. Although Emma soon realises that she is developing feelings towards him, her circumstances restrain her from becoming better acquainted with the handsome Captain. As Emma's difficulties increase, her determination to keep her family safe and united soon becomes even more burdensome, and she finds herself sinking into an even worse state of desperation.