Something is very wrong in the remote Massachusetts town of Leams.

Twelve-year-old twins Tracy and Frankie Considine have just moved into their grandmother's huge cream-coloured colonial house, surrounded by flowerbeds and towering oaks. Their thirteenth birthday is three days away, and life should be nothing but excitement and new beginnings.

But Tracy's childhood friends have changed--turned cold, secretive, hostile--ever since their own thirteenth birthdays. The family poodle vanishes into the woods and her collar turns up near a bonfire, cleanly cut and stained with blood. Strange chanting drifts from deep in the trees at night. A fortune teller takes one look at Tracy's palm and refuses to speak, handing back her money in naked terror: Be careful who you trust.

When Frankie discovers that Leams is an anagram of Salem--and that this town has been concealing a legacy of darkness since 1692--the twins realise their birthday celebration may be something far more sinister than cake and presents.

Time is running out. Frankie is stranded hundreds of miles away, racing to reach his sister before the party begins. And in Leams, turning thirteen changes everything.