The Secret of Black Ship Island
by Larry Niven
Book 1.5 in the Heorot series (2012)
Publisher: Pocket Books
The oldest children of the settlers on Avalon (that started with The Legacy of Heorot, called “Outstanding” by Tom Clancy) are now in their late teens and want independence from their parents and guardians.
They especially don’t want parents around for an initiation ceremony, held on Black Ship Island, for the younger children just reaching their teens. But when previously unknown creatures make their deadly appearance, things go horribly wrong … A novella set before the events that unfold in Beowulf’s Children.