The Xindi, an alien race from the Delphic Expanse, launched a devastating attack on Earth, causing millions of casualties and massive damage in Florida. As Enterprise returns home, an unlikely source from the future informs Archer about the Xindi and that their next attack will destroy Earth. Capt. Archer and the crew embark on a mission to the galaxy's far reaches to stop the Xindi. Complicating matters are the machinations of a vengeful Klingon still looking to capture Archer.