The reader makes a series of choices that determine how the story's main character will deal with being asked to ride the spirited Silver Sky in a horse show after being thrown in her previous competition.
In Cosham, England, in 1917, Darling, a mischievous collie, must leave the children who love her when she is chosen for training as a mercy dog, seeking out injured soldiers on the battlefield and leading medics to them.
"Leo is a hardened old sea dog who knows not to trust anyone but himself after four ocean voyages. But when he sets sail with Magellan on a journey to find a westward route to the Spice Islands, he develops new friendships as they experience hunger and thirst, storms and doldrums, and mutinies and hostile, violent encounters. Will they ever find safe passage?"--