Albert the Alien #4

During a hall monitor meeting, Gerty Greyson - Albert's homestay sister - notices the rest of the kids acting strangely. Turns out they are being controlled by an alien headpiece that turns them into zombies! Gerty and Albert must find out who is brainwashing the students and save them from the diabolical force - and at the same time, solve the mystery of the school locker thefts!