'Before the Flood,' which serves as the second part of the story that began with'Under the Lake,' suffers from the same flaws as the two-part opener for Doctor's Who's ninth season. While it starts off well and
has interesting ideas, the payoff is dissapointing.
The previous episode ended with the Doctor escaping from an underwater lab in his TARDIS and going back through time to visit a Scottish village before it becomes submerged after a dam bursts. Clara, the Doctor's latest companion, is trapped in the lab with other survivors and a small group of malicious ghosts -- actually the souls of departed people being harnessed by magnetic alien technology to send out a signal on behalf of an alien being trapped in a box aboard an excavated space ship.
The Doctor determines that the space ship is actually a hearse. The occupant of the box is a Predator-like being called he Fisher King who is attempting to summon reinforcements.
The idea of alien technology harvesting what passes for the human soul isn't exploited to the extent that it could have been. The first episode's villain, a ghost sprting mutton chops and period clothing, is reduced in this episode to comic relief (admitedly he is kind of funny).
The episode raises interesting points regarding the potential consequences of interfering with the natural flow of time. But while thought provoking, it ultimately leaves the viewer wanting.
Maybe the better ideas in this season's first four episodes will serve as a spring board for interesting future storylines.