MAP OF A SOUNDLESS CLOCK

A girl and a special dolphin lead a lost ship through space in this YA sequel.

Andi and Artie Johnston are 12-year-old twins traveling the cosmos. Andi rides her “supernatural” golden dolphin, Lux, with whom she has a mental bond. The brilliant but taciturn Artie is safe aboard the Kronos, a sailing ship belonging to Capt. Grubb and his crew. Lux is pulling the ship through space so the crew can eventually “find their lost people.” Suddenly, a mysterious armored figure approaches the ship and accosts Lux. This is Mynost, who seems to demand the dolphin’s help and transmits to Lux the image of an eye in a circle. The ship’s navigator, an aquatic selkie named Calypso, believes the image refers to the legendary Oracle, which Andi and Lux are best suited to find. Some aboard the ship don’t want them to leave, however. After several violent acts demoralize the crew—and one severely injures Donalys, Grubb’s 10-year-old nephew—Andi and Lux scout out a distant world. On it, they meet the alien Mashah. He leads them to a series of metal symbols that form the Horologium locus, which will aid in the journey. Back on the Kronos, it’s soon discovered that Mynost also covets the Horologium locus, and an unthinkable choice is made to preserve the mission. Reynolds’ protagonists may barely be teenagers, but their complex emotional travails make for elevated YA reading. For example, Andi keeps a secret from Artie about their mother’s true fate; meanwhile, their best friend, Jubal, has an abusive, alcoholic mother. The depictions of deep space are exquisite: “Each ball of sun, every pinprick of far-flung stars, and the wavy, curvy nebulae whispered to her.” Unexpected terrors, like a creature made of blood, break up ethical discussions and interpersonal drama that give the space journey a disquieting realism. The final quarter reveals a surprise enemy in the crew’s midst and some dark cosmic happenings.

A challenging thematic sequel that never talks down to YA audiences.