We open the main part of Instruments with Chris, our lovely clarinetist, who in this universe is an ex-Wind moved to Brass territory working as a bartender. Hounded by annoying Brass soldiers, he and his 'sister', Olivia (oboe), do what they must to survive.
Something happens here that causes him to take out the trash earlier than usual. I think probably the boss noticed his depressing mood and let him go a bit early, so he tried to finish his tasks early or something. But basically he goes into the alleyway and slams the door into Rosie, who is currently on a mission. She panics, because she's observed the soldier's paths and she didn't know this door would randomly open a this time.
The colour bombs she set would go off any second now. With some aggressive yelling, she runs, and drags Chris with her (because now he had seen her and knew too much). Chris runs after her, fearing for his life. He asks what will happen to Olivia. Rosie says she will send someone to fetch her later.