Adam is a serious and honest young man, the hero of the story, and as he can't stand on his own legs yet financially, he keeps his feelings for Hetty a secret (and, by the way, she doesn't notice his existence at all). The maiden is then seduced by the squire. Hetty becomes pregnant, flies the village fearing ostracism and abandons her baby in the fields. She is put on trial for child murder... Adam and Dinah, in the meantime, have gradually become aware of their mutual love.
George Eliot is not for nothing famous. She is good in characterizations and has a keen ear for dialogue. But... her style is also very long-winded. She tends to give long descriptions only for description's sake, without building any dramatic tension. Trollope would have done this much better, I thought all the time when reading Adam Bede. And although I am not against authorial intrusions (I love Nabokov, after all), George Eliot goes too far when she uses a whole chapter to discuss the "ideal preacher" - a subject about which I couldn't care less.