Lonesome Jim is the sixth episode of the first season of the animated series.
"Someone just stole the rarest tortoise in the world and the Nektons are searching for it. But the man who stole it secretly wants to capture them too! The Nektons are walking into a trap."
On the Aronaxx Will is trying to convince Ant to eat kelp when they receive a mayday call from Bob's position, after rescuing Bob and Jess it is revealed that they are transporting a Floreana island Tortoise that's named Eve, claiming that she was in a zoo wrongly mislabelled for many years and the vet reports show her healthy. They then take Eve to the only other known Floreana island Tortoise named Lonesome Jim who they bring together. After Kaiko fixes their plane Bob and Jess leave.
Will and Ant return to check on Jim and Eve but are unable to find them anywhere. Following a signal from a tracker placed on Jim the Nektons find a strange looking submarine and then receive a message from a man named Sebastian Conger who invites them to dine with him, suspicious Will and Kaiko go while Ant and Fontaine stay to find more info on Conger. Upon arriving it's revealed that Conger took Jim and Eve and that Eve is actually an animatronic that Conger designed for Jim to follow and come to him, Conger then captures Will and Kaiko.
Conger's men board the Aronaxx but are unable to find Ant and Fontaine, but while heading back Ant and Fontaine secretly hitch a ride on the sub. While sneaking through the ships air ducts Ant and Fontaine overhear Conger talking to Bob and Jess who are revealed to be in on the kidnapping, Conger asks them for assistance on preventing the Nektons from alerting the authorities but they refuse so Conger captures them to.
Ant goes to free Jim and Fontaine goes to free Will and Kaiko. While captive Bob explains to Will that he was engaged in sabotage of bulldozers which Conger found out and threaten to expose, Kaiko uses Will's commlink to override the security doors and escape just as Fontaine arrives. Ant frees Jim but due to Jims slow nature Ant has trouble getting him to the moon pool, Kaiko and Jess arrive to help but Ant is upset over Jess lying to them and has trouble accepting her help, using Eve's remote control Jess is able to Jim to the moon pool quicker but Conger realizes this and pursues them. On the Aronaxx Will calls the WTO for asstance while Ant and Jess fend off against Conger's men long enough for them to escape, Conger is forced to retreat.
Back on the Aronaxx Jess apologizes to Ant for lying to him and his family and says goodbye to him for she and Bob leave. The Nektons take Jim back to his home and adapt Eve to solar power so she'll run forever and Jim won't be alone anymore.