Rabbi Yochanan and Rabbi Elazar debate whether the court can force one who collects interest at a fixed rate to return the interest payment that he collected. Various sources are brought to prove/disprove the opinions. The first mishna in the chapter described interest forbidden by the rabbis. The case was multi-tiered and the gemara attempts to explain exactly what the case is and what makes it forbidden. Both attempts are rejected and in the next daf, Rava will bring an alternate explanation.