Disturbing.If there's one word I could use to sum up Dark Water, it would be disturbing.Doctor Who can go one of two ways. It can present something that we are completely detached from and give us a timey wimey science fiction adventure where we can pretty much check out, enjoy it, and go with the flow for three quarters of an hour. Or it can take something that is everyday to us all, and twist it to its advantage to make the story, or threat, seem very very real. I'd wager that none of us have ever been troubled that much by the thought of a Mummy on an intergalactic space train, but the fear of something hiding under the bed has more than likely popped into a fair few heads more than once.Then there's death. Something that all of us will deal with in some form or another sooner or later. The death of a loved one. The fear of our own passing. Just what is there on the other side?The theme of death has prevailed throughout series 8, and as expected it is bought to a forefront in the finale. Dependent on your own experiences then there are times in these first 46 minutes that come dangerously close to crossing the line. We know we're watching a science fiction story, but if you've recently lost a loved one then there are certain moments, especially one line - three words to be exact - that is quite difficult to hear. It's no worse than your average supernatural movie might present, but I'd argue that it's not necessarily what the majority of casual Doctor Who viewers expect during their Saturday night viewing. I imagine there will be complaints to the BBC from both sensitive and overly sensitive souls... it's a brave Steven Moffat to take on the brigade of Daily Mail readers who will likely be reaching for the phone come 9pm this Saturday.This being said, Dark Water is the finale that series 8 absolutely deserves. It's mesmerising, strong, and grabs your attention from the (quite unexpected) opening scene. You'll discover just how far the Doctor, Clara and Danny will go to for each other. To say anything more than that would be too spoilerific. But maybe if this episode teaches us anything, it is that we should take heed and listen to the ranting Scotsman in the street. He tends to know best.There were two short snippets of footage removed from the preview version, for what were very obvious reasons, but even with those key moments missing I think there was enough to take a good guess as to what was in them, and to understand that this episode does not disappoint.Withheld scenes or not, Dark Water still offers answers to questions. Questions we have asked all season long. But as not everything that was presented in the trailer is featured in this first installment, one of the biggest questions remains to be resolved. Which means as wonderful as it is to have the two-part stories return, the next seven days are going to feel like aof a long time.