Sam and Dean come to the aid of Sam's old college buddy after he is accused of a murder he swears he didn't commit. The brothers discover a shapeshifter is adopting the likenesses of others and murdering people. The brothers' race to stop the shapeshifter takes a terrifying turn when he shifts into the likeness of Dean.

When Sam and Dean receive a distressing video message from Kevin Tran, they set about trying to uncover the Third Trial. The boys make a discovery that sends them to a casino in Colorado, to find a mysterious recluse who may be able to fill in the holes in Kevin’s research. Meanwhile, Crowley is on a winning streak. Castiel tries to elude Naomi and the angels hunting him.