Frankenstein by Mary Shelly is a classic gothic story where a doctor creates a monster from pieces of bodies obtained from grave robbers. Kenneth Oppel imagined what happened before this in his novel, This Dark Endeavour where fifteen year old Victor Frankenstein uses dangerous alchemy to create an elixir found in a forbidden book in an attempt to save his twin brother with dangerous and horrific consequences.
Maybe you could write a story set in a world where drugs and medicines have been developed to bring humans back from the dead? How do you think a reanimated human would respond to the modern world and how do you think technology would be part of this? Humans and cyborgs live together in Cinder by Marissa Meyer, I Robot by Isaac Asimov and many other stories. What do you think are the implications of creating a new race to live alongside us? You could also imagine a world where other scientific advances in medicine have changed things. In The Declaration by Gemma Malley it's 2140 and special drugs allow people to live forever. This sounds great but has a sinister price - it's illegal to have children and young people are all but extinct.
Can you think of other ways science could change our world? If so, you could have the starting point for a great sinister story!