Suspense is a key characteristic of gothic literature, and there are various ways in which gothic literature will typically create suspense. For example, there will often be vivid descriptions of foggy, dark settings, and there will usually be some key, unanswered questions. There will also often be a supernatural presence, the origins and purposes of which are shrouded in mystery.
In Charles Dickens's "The Signalman", for example, much of the story takes place in the dark setting of "a black tunnel," illuminated only by "a gloomy red light". The eponymous signalman reports seeing, on a "moonlight night," a supernatural presence near the entrance to the tunnel. He says that, on that night, the supernatural presence mysteriously disappeared when he ran towards it. The darkness here helps to create suspense because the signalman is unable to tell us where the supernatural presence might have disappeared to. We are also left, of course, with the impression that this presence is always lurking in the darkness, ready at any moment to leap out. At the end of the story, we are left in suspense because there are a number of questions which remain unanswered. We do not know the identity of the supernatural figure, and we do not know if the signalman would have died if the supernatural figure had not tried, ironically, to warn him about his own death.
In Bram Stoker's "The Judge's House", there is also a supernatural, or at least preternatural presence, but this time in the form of a huge, monstrous rat. This monstrous rat first appears to the protagonist in the middle of the night. The key questions in this story pertain to the malevolent character of the eponymous judge, and the suspense builds around this character and his intentions.
In Mary Elizabeth Braddon's "The Shadow in the Corner", the suspense is also largely dependent upon the supernatural, and in this instance the supernatural takes the form of a haunted house. Key events in this story, as with the other two, also take place in darkness. It is in the middle of the night, for example, that Bascom sees a sinister shadowy figure in the room.