Wolfsbane

In 1936, an amnesiac incarnation of the Doctor stumbles into a plot built around a woman convinced she is the reincarnation of Morgan Le Fay, while an earlier self's TARDIS briefly and accidentally strays into the same year, dropping off his old companion Harry Sullivan to lend a hand. Neither Doctor recognizes the other, though Harry notices something oddly familiar in the stranger he has just met. A Past Doctor Adventure that quietly crosses two incarnations without either one noticing.