If you want to read a novel that feels like a puzzle, look no further than Thomas Olde Heuvelt’s ORACLE (Tor Nightfire, 376 pp., $29.99). The novel, which is translated from the Dutch by Moshe Gilula, opens with two friends, Luca and Emma, who one morning spot a hulking shape in the middle of a flower field. The object is the Oracle, a sailing ship from the 18th century. Curious, Emma goes down the ship’s hatch and vanishes in the darkness beyond. She never comes out. Soon, others — including Luca’s father — and a handful of police officers suffer the same fate.