"Bloooo" is the thirteenth episode of the first season of Foster's Home for Imaginary Friends and the 13rd and last aired and also the 8th produced episode of Season 1.
Mac and Bloo play in the storm until they catch a really bad cold. Frankie drops Mac off at his house and Bloo turns from blue to white making his friends think he's a ghost.
Mac and Bloo are playing in the mud during a thunderstorm, and both quickly develop colds. After seeing that Mac appears to be developing a fever, Frankie gives Mac a ride back home while Bloo, Wilt, Eduardo and Coco prepare to watch a late-night horror film, but Bloo's cold gets worse and he goes to bed. Meanwhile, Frankie drops Mac off at his home, and during her drive back to Foster's she swerves off the road trying to avoid hitting a large figure with a hook on his left hand. Frankie gets out to investigate, but doesn't find anyone (unbeknownst to her, the figure's hook is now on the bus' rear bumper).
Back at the house, Wilt and Eduardo are beginning to believe the ghost in the film is real, and both get startled when the window behind them blows open. In a state of panic, they barricade all the windows and doors of the house, with Wilt throwing the keys outside. Frankie returns and hurries up the path, but slips up and loses her key in the mud. When she searches for it, she finds the keys Wilt threw out. Wilt and Eduardo try to go back to their room, but encounter what they believe is a ghost in the corridor (in reality it is Coco wearing a sheet) and flee. Whilst hiding in their room, they see and hear what they believe is another ghost (in reality a very pale Bloo).
Outside, Frankie finally manages to unlock the front door, but cannot get inside because the door is barricaded. Back inside, Wilt, Eduardo and Coco plan to catch the "ghost" themselves, using a vacuum cleaner laid by Coco. Whilst sneaking through the house looking for the "ghost", they encounter Bloo again and begin chasing him. Meanwhile, Frankie is still outside trying to get back in, and whilst looking for a way back inside she sees the silhouette of the figure she almost hit earlier, and runs away screaming. Wilt, Eduardo and Coco eventually corner Bloo and attempt to capture him using the vacuum cleaner, but Eduardo accidentally activates the blow function, sending Bloo up into the air. Bloo grabs hold of a chandelier, but eventually loses his grip and falls to the ground, where he is caught in a potato sack Eduardo was carrying.
In the foyer, the group is confronted by Mr. Herriman, who has been investigating the disturbances and demands to know what is going on, with Coco explaining that they have caught a "ghost". Just as Mr. Herriman claims ghosts don't exist, Frankie rams the front door with the bus in a last-ditch attempt to get inside, and in doing so covers the group in plaster. Frankie gets out of the bus gibbering about a monster, and, upon seeing the group covered in plaster, screams that they're ghosts and faints. The figure outside pushes the bus further into the house and retrieves his hook. In a deep, sinister voice he claims he's been trying to get his hands on them all day, which causes the rest of the group to faint. But the figure clears his throat and reveals himself to be an imaginary friend looking for a home. Bloo gets out of his sack and confirms they take in imaginary friends, with his pale colour scaring the friend and causing him to flee.
The episode ends with a confused Bloo sneezing at the camera, whilst a montage of the characters screaming is played over the end credits.
Home Video releases