The Treasure Island of Dr. McLean

'''The teams wake up in the middle of the lake, where a returnee starts mutating due to toxic exposure, and seeks help from a fellow teammate. Meanwhile, another member tries to help a friend keep his secret under control. Someone is revealed to have found the idol, and asks someone else to keep it a secret. The finder is eliminated, but uses his discovery and his new friend to eliminate a mutant instead.'''

Plot
The episode begins with the camera panning at both teams sleeping on rafts out in the lake. Scott doesn't seem to remember anything after dinner. Cameron goes into a flashback when being served the "Turkey Butterlini", where he remembers Chef telling Cameron to enjoy his nap, before correcting himself and says meal. Mike then finds a fedora hat and puts it on, causing him to turn into Manitoba Smith and starts talking to Zoey. Cameron pushes her in the water and takes off the hat for Mike, in order to save their relationship. He makes a confessional about how he helps Mike with his disorder, and in return he helps him get rid of Scott. He also knows all the ways Mike goes into his different personalities, but hasn't mastered getting his original one yet. Dakota also makes a confessional. She states that now being bald, she has to focus on becoming friends with the rest of the contestants. She chooses Zoey as being the best choice to be seen out in public, post-makeover.

Chris then arrives to start the next challenge, but Dakota interrupts him and starts revealing embarrassing things she learned about Chris while being an intern. However, no one pays attention as Dakota grows larger and her hair started to grow back, only that now in a neon green color. Chris then gets on with the challenge saying first that the Chris immunity statue has been found, and that the teams have to first race back to shore to earn a reward to use for the second part of the challenge. While rowing, Lightning runs into a mutated squid, slowing down the Rats. Meanwhile, Fang has found the Maggots, but Dakota punches it with her new strength into the squid's eye, freeing the Rats from it's tentacles. After the Maggots reach the location of the squid, it starts attacking them. Cameron then comes up with a plan to hit the front of the board launching everyone on the back to shore.

Once ashore, Dakota starts to look for Chris and is already seen even bigger than before, and starts to jump for Chris in the helicopter. He dumps the rewards the Maggots won to them, a compass and a map of the island. Lightning and Jo are seen washed up on shore as Chris continues saying that now the teams have to find the chest in which Gwen is buried alive in, along with Sam, who was knocked out by the meal the night before as well. Once seeing Sam knocked out, Dakota becomes angry and mutates further with an increase in height, orange skin, and even grows a tail. Chris allows the Maggots to head out, but stops the Rats. He gives them the "Penalty Belt" and gives them a metal detector. Jo states how that would be of any use to them as the chest is made of wood. Chris replies that it isn't and sets them off.

Back in the chest, Gwen calls Chris with her cell phone. He answers and makes fun of the farting noise in the background from Sam, which knocks her out. The Maggots get to a swamp that blocks their way. Mike finds a path out of the swamp and Cameron and him start to swim. Scott tries to make his team lose by showing the way through the swamp for the Rats. Dakota grabs Zoey and starts going to the water, but Scott reminds Dakota that Sam is losing air in the chest, which makes Dakota drop Zoey and race for Sam, leaving Scott and Zoey alone. Scott says he trusts Zoey enough to show that he has the immunity idol. Zoey is flattered by the fact he trusts her that much. He then tells her at least he doesn't hide things from her like Mike, and tries to make it seem like he is the only trustworthy person on her team, then they both go into the water. Later on, the Rats finally make it to the swamp. Jo sees the arrow Scott made and follows it through the water.

Back on the Maggots' team, Mike and Cameron try to tell Zoey not to trust Scott, but Zoey ignores them, still believes that Scott is a nice person, and doesn't notice when she walks onto the back of a giant mutant alligator, which startles her and her team, making them run in order to find a nearby tree. Scott and Cameron climb up, while Mike turns into Svetlana to get up, leaving Zoey by herself. She screams for Mike, which results in him turning back into himself, because of which Cameron figures out how Mike reverts back into himself and grabs Zoey. Dakota then fights with the alligator to save her team. While trying to find a way out of the swamp, Zoey asks for the compass after realizing that they had dropped the map back in the swamp but Mike tells her that he doesn't have it. Scott admits to having the compass in the confessional and attempts to hide it.

Lightning sees Dakota fighting and brags about how he could do the same, which Jo mocks as more alligators show up and start attacking him. Cameron tries to find an alternative to help the team to get out of the situation, which ends up being a thorn forest, and Dakota clears a path while fighting. Mike's shirt is caught on one of the thorns, turning him into Vito, and calls out for Anne Maria. Zoey stops and seems upset of hearing Vito again, but Cameron tries to pull his shirt back down. Jo and Lightning both get out as well and find a key under a rock with the metal detector, one for the belt lock, and one for the chest. Jo then hears Gwen underground and starts digging, while Scott tries to make his team dig away from the actual location of them, but Jo had already found Gwen, making the Rats have their second win of the season. Dakota then reaches for Sam in the chest, after tossing Gwen aside, and Sam wakes up to her cuddling him. Sam then states in the confessional that he thinks Dakota has gotten even more awesome.

Later that night, at the campgrounds, Dakota and Sam are seen spending time away from the rest of the Maggots, while Mike pulls Zoey over to say that they need to get rid of Scott, but Zoey is still unsure know who to vote for. Scott tries to get the secret about Mike by saying to Cameron that he appreciates that he helps him. Cameron didn't know it was a trick and tells him that Mike has Multiple Personality Disorder.

At the elimination ceremony, Dakota first asks if Sam still likes Dakota, Sam says he'll always like her, and they make out, disgusting the other campers. Chris then tells that the camper voted off was Scott. He then pulls out the Chris idol, making Chris go to the next highest voted person, which happened to be Dakota with one vote, from Zoey, who didn't like her friendship that could potentially hurt her health. Dakota doesn't seem to care anymore about the show because of being too occupied with Sam and takes the Hurl of Shame.

Exclusive Clip
At a locker room (which resemble the Aftermath show's green room), Sam is seen complimenting Dakota's mutation as the latter prepares for her wrestling match. She then kisses Sam on the cheek and runs through the door once they called her name.

General

 * With Dakota's elimination, all of the remaining contestants go on to qualify for Total Drama All-Stars.
 * This is the sixth episode in the series to reference a character's name in the title. The others are The Chefshank Redemption, Super Hero-ld, Crouching Courtney, Hidden Owen, 2008: A Space Owen, Aftermath: Bridgette Over Troubled Water, and later on Grand Chef Auto, Zeek And Ye Shall Find, Scarlett Fever, and Sky Fall.
 * This is the first episode that Dakota wears her original outfit since Ice Ice Baby, as she is required to wear an intern outfit from Finders Creepers through A Mine Is a Terrible Thing to Waste.
 * Sam returns in this episode as a part of the challenge.
 * This makes him the second new contestant this season to return as something other than be a contestant. The other is Dakota whom Chris used as his intern.
 * Scott makes more attempts to throw the challenge in this episode than in any other episode to date, as he does so three times:
 * He drew an arrow on the ground to point the rival team in the right direction.
 * He stole their compass and rendered them temporarily unable to find out which way to go.
 * He tricked them into digging in the wrong spot entirely, which finally succeeded in making them lose.
 * The giant mutant squid that appears in this episode briefly appears in the opening sequence.
 * The map the Mutant Maggots got was the same map Gwen used on Boney Island in Trial by Tri-Armed Triathlon, and the compass was the same as what Gwen and Heather had in Are We There Yeti?.

Continuity

 * This is the second episode this season in which the Toxic Rats win a challenge. The first is Finders Creepers.
 * This is the second episode in which the contestants wake up in the middle of the lake. The first is Camp Castaways.
 * This episode marks the only episode of the season in which a bonfire ceremony that results in a contestants' elimination occurs and Lightning does not attend.
 * This is currently the only episode to feature two former contestants as part of the challenge.
 * Gwen's exclamation about being "buried alive again" is a callback to her challenge in Phobia Factor.
 * This is the second episode in which Gwen has to face her worst fear.
 * This also shows that like Owen in Total Drama World Tour, Gwen hasn't fully conquered her fear from the first season.
 * With this episode, Dakota has taken the Hurl of Shame three times and Sam has taken it twice.

Goofs

 * When Dakota punches the shark into the squid's eye, it has a black eye. However, it later disappears.
 * On iTunes, this episode's title is incorrectly spelled "The Treasure Island of Dr. MacLean".
 * Chris told Jo that the chest Gwen and Sam were located in is not made of wood. However, chunks of wood can be seen flying everywhere when Dakota breaks it.
 * The iTunes description for this episode says that Dakota's hair grows back bright orange. It is actually her skin that turns orange, while her hair is bright green.
 * When Cameron is asking why Chris didn't hand out the marshmallows, Dakota's top is the same color as her pants. In the next scene, when she admits she ate them, it changes to its usual light pink.