The Doctor follows Claras connection to Danny but it is perhaps Claras connection to Missy that will prove to be more important. The Mausoleum is a rather brilliant callback to a Patrick Troughton episode from 1967 called Tomb of the Cybermen. In that story the cyberman are preserved underground in ice filled cubicles. Is a cyberman alive? If a mind is stripped and violated to the point that its individuality ceases to exist does it become nothing more than an engine to drive a metal suit? Missy delights in pretending to be an android but she may be closer to one than she is willing to admit. If your focus is rigid and your goal singular are you not locked into a set program? The difference between woman and machine is not a question of intellect but one of empathy.