The "monster" in The House of the Seven Gables is the evil, greedy spirit of Colonel Pyncheon, which travels down the Pyncheon line to Judge Jaffrey Pyncheon. At the start of the book, siblings Hepzibah and Clifford seem to be in a poor position to fight Judge Pyncheon. Hepzibah has been living quietly on her own for three decades while Clifford has been sitting in jail cooling his heels. Nonetheless, both of them begin to try to make happier lives for themselves: Hepzibah opens her store and Clifford attaches himself to Phoebe and enjoys the blooming Pyncheon gardens.
As Hepzibah tries to make a good life for Clifford, she finds herself fueled with unusual strength. The monster, Judge Pyncheon, arrives to offer Hepzibah financial support as long as he can visit Clifford freely. Hepzibah finds the resources to tell Judge Pyncheon no – he can't bother her poor brother. This refusal works – for a time.
Despite Hepzibah's efforts, Judge Pyncheon comes back to the House of the Seven Gables. What's more, the person who helps Hepzibah and Clifford get through this difficult time, Phoebe, happens to go on vacation just when the monster next rears his ugly head.
Finally, in Chapter 15, Judge Pyncheon refuses to be put off. He storms into the House of the Seven Gables, settles into the parlor, and will not leave until he sees Clifford. How will they escape?
Judge Pyncheon suddenly falls victim to exactly the same weird, bloody stroke that killed his ancestor, Colonel Pyncheon. With Judge Pyncheon's death, Clifford and Hepzibah are free to leave the House of the Seven Gables. They inherit money, Clifford's name is cleared, and the three remaining Pyncheons (Clifford, Phoebe, and Hepzibah) settle down in Judge Pyncheon's beautiful country house.