Tip of the Iceberg by Ash Hartwell

Esme Jackson grew up in the slums around the Southampton docks with dreams of travel and a better life for her sister. Bridget Grafton was born to Boston wealth and married to an arrogant, violent English industrialist. The two young women board RMS Titanic for her maiden voyage. Separated by money and divided by class, their lives become fatally entwined by a single act of humanity. Murder, deceit, betrayal, and friendship—all set against the violent destruction of the social order in the face of a rapidly spreading deadly virus. The voyage quickly becomes a struggle for survival...