Fantastic literature can often be seen as a writers attempt to tell us what ought to be done in order to keep the world out of the hands of evil. In the case of Stoker's Dracula, the novel can be read as symbolic representation of virtues and tools needed to keep the prosperity of London safe.
Dracula is a representation of pure evil. It desires to come to London ("I long to go through the crowded streets of your mighty London…" p. 60) . Why London? London seems like an allegory of Eden. A Place that is embraced by objective (modernity and prosperity of the developed city) and subjective good (cosmopolitan city with Lucy’s, Mina’s and Jonathan’s stories of love; lunatics hidden behind the bars). This perfection is ruined by a coming of Dracula. Evil works in many ways so there are many things needed to defeat it. What is crucial here is the author's choice of characters: the protagonists could be randomly picked through the story, but we can see their roles of love, revenge, money, science, and experience. And - as it is omnipresent in almost every breath of the book - the most important are faith in God ("…we go as the old knights of the Cross…" p.398) and artifacts of Christian rituals. Maybe only outsider can help us see things we don’t (Van Helsing) and maybe we’ll need to face our deepest nightmare (Jonathan’s return to Transylvania). These are Stokers weapons of choice and with everyone playing their role, London is saved.
This reading thus brings such level of understanding the work: It’s a reminder towards the inhabitants of London that they should not forget to deepen their religion and scientific knowledge (among other things) due to the dangers superficial beauty of the city might attract. As we saw, some elements direct us to Stoker as a critic of Victorian London.
Bram Stoker (1847-1912), photo: http://commons.wikimedia.org