An investigation is underway after an 18-year-old high school senior died aboard a Carnival cruise ship. Detectives are reviewing video from the ship and interviewing passengers as the victim's family searches for answers. David Muir reports. https://abcnews.go.com/ | ABC World News Tonight with David Muir

HAPPENING NOW: President Trump attends a wreath laying ceremony and delivers remarks at Arlington National Cemetery. https://abcnews.link/tUte2YS | ABC World News Tonight with David Muir