Things aren't looking good for 4X. With another teacher running away screaming (literally), Arlo wonders how long the new supply teacher will survive. Maybe it's her animal skin dress or bone earrings, but Mrs Ogg doesn't quite seem to be the teacher anyone is expecting. When a trip to the zoo is organised, Arlo realises this might be a chance to prove to Ms Weebly, the headmistress, that 4X can behave and finally get to go to the end of year party. Only Mrs Ogg fails to mention that this particular zoo is full of prehistoric beasts!