Books The End (series of unfortunate events book 13) by Lemony Snicket (Author),

The End, the 13th and final book in Lemony Snicket's "A Series of Unfortunate Events," is set on a castaway island where the Baudelaire orphans and Count Olaf are stranded among islanders attempting to create a peaceful utopia. The story involves a mutiny against the island’s ruler Ishmael, who inadvertently releases a deadly fungus called the Medusoid Mycelium, infecting everyone on the island. The Baudelaires discover that the cure for the fungus is found in bitter, hybridized apples on a tree in the arboretum.

Despite their efforts to save everyone by distributing the apples, most islanders decide to leave on a canoe with Ishmael, who refuses to share the cure despite having taken it himself. Kit Snicket, a friend who is pregnant and succumbing to the fungus, gives birth to a baby girl named Beatrice before dying. Count Olaf dies after helping Kit to safety. The Baudelaires take care of the baby and eventually decide to leave the island to honor their parents' wishes, setting out into the unknown with hopeful yet uncertain futures.