"Cold Feet" is the twelfth episode of season two and the twenty-fifth episode overall of the animated children's series The Magic School Bus. It originally aired on November 25th, 1995.
Liz has disappeared and the trail leads to Herp Haven, which is some kind of spa for reptiles. There, they see a woman named Mrs. Westlake ask for her turtle to be "toasted and stuffed, just like the last one." They decide to lead a rescue mission to find Liz, on which they learn about reptiles and how they need to move from place to place to get comfortable because they are cold blooded, which comes in handy, as Ms. Frizzle turns them into some!
Phoebe is seen rushing to the school to bring Liz home, only to discover that Liz is missing, with the rest of the class going on an exhaustive search for the class lizard. All of Liz's belongings are missing, as well as her entire habitat, and Ms. Frizzle arrives wearing an alligator suit, completely cognizant of Liz's absence. The rest of the class are shocked of the teacher's lack of concern for Liz, and Wanda finds a note behind the trash can, only to discover that it is written in esoteric lizard drawing. Ms. Frizzle reads the material Liz wrote on the note and the class is convinced that Liz moved out. Arnold comes across a sheet with the address to a place that appears to say "Herp Ha" (since the other part of the "Ha" is torn out). When Ms. Frizzle informs to the class that a herp is a reptile, and since Liz is a reptile herself, Phoebe wants to know what it is like to be a reptile to get an experience of how Liz feels.
This prompts Ms. Frizzle to lead the class to the bus and drive to a place called Herp Haven, and Ralphie views a sign that says "Alligator Crossing". Just then, the gate opens, and a limousine enters and stops inside the place. A chauffeur exits the limousine and escorts a woman named Mrs. Westlake out front the back with her ponderous pet turtle. When Mrs. Westlake arrives to the edifice of the house, she tells the owner she wants the turtle "toasted and stuffed", which convinces the class that the turtle is about to be served for dinner, and Liz might be next. So Wanda rings the doorbell dressed in a baseball uniform and tries to persuade the man, who answers the door, if she could get her lost baseball from his yard. The man says that she needs the optimum body temperature in order to enter his home and rejects her offer.
Since all reptiles are cold-blooded, Ms. Frizzle transforms the bus into a Trojan alligator, with Phoebe hauling it to the front door. She answers the door and the man invites Phoebe and the Trojan alligator bus (which Phoebe call Valerie, Ms. Frizzle's first name) inside. The man takes "Valerie" inside a secret room and tells Phoebe that he will "let her know when she's done", much to Phoebe's horror.
Phoebe sneaks inside the room to search for Liz and "Valerie" is taken to a room with a habitat for reptiles. "Valerie" swims in the water and the class discover different types of reptiles. Ms. Frizzle then transforms the class (with the exception of Arnold and Dorothy Ann who take control of the busagator) into reptiles: Ralphie a turtle, Carlos an caiman, Keesha a garter snake, Tim a gecko, Wanda a chameleon, and Ms. Frizzle an frilled lizard. They continue their search for Liz and open a mysterious door. When they walk inside, the busagator Arnold and D.A. are inside comes across an alligator, who seldom attack human beings according to D.A.'s research.
Meanwhile, Phoebe comes across the kitchen where a chef is cooking food for the reptiles. Phoebe enters the kitchen as soon as the chef leaves and is appalled of the servings each reptile is getting. The rest of the class come to a boiler room and don't sweat due to reptiles not having any sweat glands.
Back in the reptile habitat, Arnold and D.A. feel cold due to being inside the busagator. So they attempt to move the heater to the busagator, only to get followed by the other reptiles. They return inside the bus to avoid the reptiles. The rest of the class enter the quiet room to finally find Liz sleeping inside a tank. They try to wake Liz up, but the sleeping lizard doesn't budge, and Keesha informs that she can't feel Liz's heartbeat as the rest of the class begin to worry.
The class surmise that Liz is probably frozen and learn that reptiles can't shiver, but rather have their bodies slowed down, which is tantamount to hibernation. The rest of the class begin to slow down as well and fall into stupor. Phoebe enters the quiet room and picks up Liz and the rest of the class as they slowly regain consciousness thanks to Phoebe's warm body carrying them. Phoebe runs through the hallways, only to run into the man, who chases after her. Phoebe hides inside the reptile habitat room and finds that the busagator is hibernating too, and Arnold and D.A. are shivering inside. The rest of the class moves to the heater and hops inside of the bus for Phoebe to haul the busagator to the heater, where it finally gets enough energy to regain consciousness.
The busagator makes it out the back door, only for a trio of alligators to approach their way. So Ms. Frizzle transforms the bus into a bigger alligator and attempts to escape, only for the man named Harry Herps to offer them Liz's habitat (which Harry is revealed to have built for her), which he was repairing to make Liz feel cooler and more comfy. Ms. Frizzle explains to the class that Liz was staying at the Herp Haven to get her habitat fixed and she wanted the rest of the class to find out for themselves.
- This is the first time the class (except Arnold, Dorothy Ann, and Phoebe) is transformed into animals.
- The shot of Liz hammering and the producer receiving a phone call was re-used for the second half of "Holiday Special".
- For some reason, the audio has a lower pitch during the first minute but remains normal for the rest.
- The TV tie-in book was called "Gets Cold Feet".
- We learn how Liz's habitat was built.