Walt is suffering from insomnia, worried about the choices he has made and the direction his life has taken. Unaware that Jesse has been skimming a bit of their product, he also worried that the numbers in his formulas don't add up and that they always seem to somewhere between 4 and 8 ounces short of what the batch should have produced. The meticulous Walt is also concerned - to the point of paranoia - when he discovers a housefly in the lab. Worried about contamination, he goes to extreme lengths to kill it. Jesse comes to his rescue in an interesting way.