Book 15

In the book Harry Potter and the Chamber of Secrets (pg 151-end) it shows a great theme of forgiveness.  In the book, Harry and his friends realize if they can make a polyjuice potion, they can get the truth out of Malfoy. The next day is the Quidditch match and there is a rouge bulger chasing after Harry, and making it impossible to do anything. Especially with George and Fred keeping the bulger from getting him.

When Harry sees the snitch and stops for a second the bulger hits him straight in the arm but Harry lunges at the snitch with his free hand and it worked. Sooner on in the hospital wing he sees Dobby that admits that he riged everything and hurt harry. And Harry soon sees a petrified Colin Creevey levitated into the bed next to him. Soon in dueling club Harry realizes he is a parselmouth and people think that he tried to kill Justin Finch-Fletchley, and later saw him and Nick petrified. And got caught in the act. When they use the polyjuice potion Malfoy does know one thing about the chamber of secrets.  

Soon Harry found a diary that can talk to him and showed him how the chamber of secrets was opened 50 years ago.  Hermione and the Ravenclaw seeker were petrified, and Ron and Harry went to go see hagrid right before he and dumbledore got arrested and had to follow the spiders.  And when they did they found aragog, and he told them about hagrid. Once the potion for the paralyzing was done, Harry and Ron went to go see Hermione and realized the thing in the chamber of secrets was a basilisk and the chamber of secrets was in moaning Myrtle's bathroom and that was how she died. When they went in the chamber of secrets lockhart he tried to obliviate with Ron’s wand. But the spell backfires and wipes his memory.  When Harry finds Tom Riddle and the basilisk he stabs the dairy with the basilisk tooth it lost biting him. And destroys the horcrux. In the final chapter Harry sees Malfoy's father and gives him back the diary, and when the Malfoy makes Dobby hold the diary he opened it and finds a sock and Dobby was freed and protected Harry from Malfoy.