My last duchess poem

hello , please will someone help me , i have to write an essay on the peom " My last Duchess" by robert browning , i have to answer this question

Choose a poem in which there is a sinister atmosphere or person or place. Show how the poet eveokes this sinister quality and discuss how it adds to your appreciation of the poem.

i have chosen to write about the duke and how he seems sinister , but i dont have a clue what i need to write and put into the essay , its to be in for tommorow , i am doomed unless someone would like to give me a couple of hints as to what i can write .

plz answer , i will be very thankfull if you did xx