Find the portrait on the fifth floor of the Grand Staircase that rhymes. He will tell you to find the portrait with three faces. Head to the seventh floor corridor and find that three-faced portrait. He will tell you to ask Professor Basil Fronsack. Go to the third floor and ascend the stairs to the Defense Against The Dark Arts room, but stop at the talking gargoyle. Take the passage beside him. Proceed until you reach the portrait just before the Charms room. He will tell you to find the shepherdess on the second floor landing. Go back the way you came, but go through the door on the left before you reach the stairs to third floor. Go down the stairs until you see a portrait of a lady in pink with a staff and sheep. She says to see Google Stump in the Viaduct Entrance. Once there, go to the only portrait in the area, next to a bookcase. He says to ask Gifford Abbott. Go all the way down the stairs in the Grand Staircase. He is the last portrait before you get to the entrance. He tells you that the password is "This password is absurd." Go back to Pratt's portrait and tell him.