Arriving back at the treehouse Numbuh 5 finds out that the Common Cold has infected the Treehouse Security System And turns the defences against her so Numbuh 5 is tasked to get through the snot infested Treehouse to try and turn off the Treehouse Security System, defeat the Flu Bugs and W.A.T.C.H.B.O.T.S and free Numbuh 4.