This is an automatically translated description

The newlyweds Simon and Lynette Doyle are embarking on their honeymoon on the steamer Carnac. Jacqueline de Belfort, Lynette's old friend from whom she had stolen her lover, decides to spoil their honeymoon with her presence. One morning, a maid finds Mrs Doyle dead... Someone has shot her in the head while she was sleeping. A bloody letter "G" remains on the wall next to the dead woman. However, Jacqueline has an ironclad alibi. The famous charismatic detective Hercule Poirot intervenes in the case. It turns out that almost all the passengers had a motive for the murder. Almost every one of them is hiding something, and several of them are known to be travelling with weapons. So who is this cold-blooded killer who does not stop at one crime?