Found it. Rule 6.05(n) With two out, a runner on third base, and two strikes on the batter, the runner attempts to steal home base on a legal pitch and the ball touches the runner in the batter’s strike zone. The umpire shall call “Strike Three,” the batter is out and the run shall not count; before two are out, the umpire shall call “Strike Three,” the ball is dead, and the run counts. So when a runner stealing home is hit by the pitch, the pitch counts and the run scores if, presumably, he touches home before being struck by the pitch. Since it's a dead ball rule, if it strikes the runner BEFORE he touches home I would assume he would have to go back to 3rd base.