When focusing on the main objectives, Aviary Attorney is about 4½ Hours in length. If you're a gamer that strives to see all aspects of the game, you are likely to spend around 7½ Hours to obtain 100% completion.
A letter arrives at the office from Séverin saying that he has either been captured or killed the previous night during his investigation of the Croc-Monsieur. You set off to save Séverin, despite his possible already-occurred death. The letter mentioned the Rue des Marmousets, so that's where you begin.
Go to Rue des Marmousets. Examine bloodstain in alley. Enter Notre Dame. Bribe Kwark with money, use box of chocolates as gift, or intimidate him. Pick any route.
You have two days to investigate the photographer's studio and the scene of the crime; these can be done in any order. If you visit La Conciergerie during this time, Kwark will turn you away as visiting hours are over. Returning to the A.A. Offices causes Sparrowson to prompt you back to investigating.
She lets all three of you go free, and has Pierro and Fontaine guide you out. Beaumort stays behind to get the truth out of the wolf brothers. They want a world without class or religion, where only reason reigns, like Beaumort's rebellion, but they believe it's only achievable with violence.
Falcon shows up late to the Aviary Attorney office and receives a letter from Seigneur Purrtoir Demiaou asking for legal help for his daughter, Dame Caterline, wrongly accused of murder. Your assistant, Sparrowson, asks if you'll be taking the case. If you respond "Of course!" you will proceed to La Conciergerie, the prison where Caterline Demiaou is being held. If you choose "Nope" Sparrowson will challenge you to a game of Jacques-noir (Blackjack) where you try to get closer to 21 when drawing cards than the dealer. Sparrowson will always win, and you'll head over to La Conciergerie anyway.
To get ending 4A, stay silent and let Beaumort shoot Séverin.
If you go back after talking to Neighthan, Silvius and Remus will be there arguing. Silvius returns Remus's green pen, which he borrowed since he lost his own. Falcon asks Remus about the catacombs and Remus mentioned another bird came by asking about secret entrances - a prosecuting rooster. He dismisses you with a threat and leaves. Sparrowson does manage to steal the fountain pen from Remus and add it to your evidence folder.