Perhaps Mina is the one who is the stranger at the Westenras and is waiting for news from Jonathan Harker?  Her chum Lucy is sleep-walking again which is probably not the best problem to have at this time.  She bumps into the tedious old bloke up at the Abbey once again and chats about this and that, especially the morbid humour of said bloke.  He apologises - almost.  Out at sea there's a storm brewing and the coastguard chap who turns up opportunely has spotted a Russian ship bobbing up and down like nobody's business. Who's at the tiller? Nice steak!