Christina and Clara refused to stay behind as well. Even though they usually didn't see eye to eye with each other as rivals in love, they never wished for such a fate as that which befell Diana. The biggest reason that they were unwilling to stay behind was that they didn't want Zach to be thinking of another woman even if it was because of his guilt and remorse when he was by their side.
Zach didn't refuse their wishes to accompany him to the sea and boarded the other boat in a hurry with the girls following right behind him.
The engines of the torpedo boats whirred at the fastest speed they could muster and set out for the location that the blip indicated on the map. It had yet to move after it stopped in its place. Therefore, Zach kept on praying that the blip would stay in the same place as he carried out his plans.
