A novel written and set in 1930s Moscow, The Master and Margarita is a veiled criticism of the repression of artistic licence and religious expression under Stalinism. But you won't sense that immediately - instead, you'll be trying to work out how the three plots in the book have any relation to each other. The central theme is the Devil's visit to the city with his retinue of demons and witches; intent on an orgy of chaos, he sets about murdering some, banishing or frightening others, and creating an atmosphere in Moscow of disbelief and hysteria. If he is a depiction of Stalin, so the "Master" (a reclusive author of a novel about Pontius Pilate who has wound up in a lunatic asylum) and Margarita (his bold and hedonistic lover) may represent Bulgakov himself and his third wife, Elena Sergeevna Shilovskaya. The third theme is the historical narrative of Pilate's judgement of Jesus - a story that is written by the Master but dreamt or imagined by other characters.
It's a difficult web of sheer fantasy, comic absurdity and references to real people whom Bulgakov knew and were either oppressors or the oppressed under Stalinism. But it's also about the power of narratives to restructure reality, and the struggle of writers like The Master (Bulgakov) not to be bowed into writing only what the authorities will permit. I'd argue that you don't need to be aware of the book's many references to enjoy it. Read it for what it is - a darkly comic tale where anything is possible (after all, Satan and his demons are directing the proceedings) - and don't bog yourself down with the references until a second or third reading. Instead immerse yourself in the novel's rich imagination, refusal to be realistic or dry, and biting satire of conformists. Recommended.