When Liv lands an all-expenses-paid opportunity to study aboard the luxury cruise ship The Eos for a semester, she can't believe her luck. Especially since it will offer her the chance to spend time with Will, her ex-best friend, who's barely spoken to her since the night their relationship changed forever. But as soon as she steps on board, Liv realises just how out of her depth she is. With Will, with the rest of the Seamester students - including the brittle and beautiful Constantine, who may be hiding his own ties to the Eos - and most of all, with the Sirens, three glamorous and mysterious influencers who seem to have the run of the ship.