Nimh: the Unauthorized Sequel - is a professionally drawn Graphic Novel and the Unofficial Sequel to Don Bluth's The Secret of Nimh.
After a dream - Mrs. Maia Brisby is disheartened to find that she is remembering less and less about Jonathan. Her daughters Teresa and Cynthia and to some extent son Martin attempt to cheer up - but are interrupted when her younger son Timothy comes in with big news: another rat survivor from NIMH (Arthur, a mechanical expert) has been found. Mrs. Brisby is intrigued by him - but he has big news. Arthur told the Brisbys about that he realized that Nash (another of the late Jenner's henchmen) is spying on them. Nash has come back for revenge. Fortunately, there was some good news as well. Soon after Nicodemus, the leader of the rats at the time, had died, the rats discovered he wasn't the real Nicodemus. He was an evil wizard named Pontius who, jealous of the legitimate Nicodemus, had tied up the latter and had him sent back to NIMH, where he was put in a better cage, with a padlock. Arthur told the Brisbys that he needed help to rescue him.
One day - when Mrs. Brisby was out - Timmy and Martin sneaked out to play with Jeremy the crow. However, the two boys got caught by Heather, a lady rat who plotted to rule Thorn Valley. She took them to her cave with Jeremy close behind. But Jeremy got caught by one of NIMH's top scientists, Dr. Hans Schultz and his assistants George and Julie. Meanwhile, Maia Brisby walked right into Justin (the current leader of the rats) who told her that Timmy and Martin are in danger. He then gave her the Red Stone Amulet to give her power.
At Dr. Schultz's camp, Justin had helped Jeremy escape. Suddenly Dragon the cat who ran away from his owners attacked them. Luckily, Jeremy flew Justin to safety, and later on, they joined up with Mrs. Brisby to find Timmy and Martin.
Mr. Ages, meanwhile, came to the Brisby house to help Arthur, Teresa and Cynthia go to rescue Nicodemus. They tracked down Dr. Schultz, George and Julie, but realized that they could never sneak into the car unnoticed. Luckily, they heard a tap-tap-tap on a nearby tree, and it was a pileated woodpecker named Nolan. They told him of their situation, and at first he didn't show much interest--until it occurred to him that if he helped them, he'd be a hero to this Nicodemus fellow as well. Nolan was able to carry Mr. Ages, Teresa and Cynthia, and realizing that he'd need someone bigger for Arthur, who at fourteen ounces was large and burly for a rat, asked his friend Sally, a great blue heron, to tend to him.
One night - at Heather's cave - Maia found her two boys and freed them. Justin got caught by Nash himself and the two rats fought. During their duel, Nash told Justin about how that wasn't the real Nicodemus who had gotten killed by the falling cinderblock, and that Jenner had been trying to restore order. Justin laughed at the idea, saying that Jenner had been evil and everyone knew it. Alas, he had to eat his words when he saw, swooping towards him, Sally the heron, with Arthur and the real Nicodemus--a middle-aged rat clad in a brown robe, with a patch over where his left eye had been, with a satchel slung over his shoulder, containing the same type of powder that the rats and Maia had used to drug Dragon--on her back. Maia realized that this explained everything--why the amulet had burned her hands the first time she'd used it, and why Pontius/"Nicodemus" never caught onto Jenner's plot to off him. The Brisbys decided to flee from the cave - but were stopped by Heather's assistant, yet another of Jenner's henchmen, McGrew, armed with his dagger. The boys ran out of the cave with Jeremy. As McGrew and Mrs. Brisby fought - some rocks came crashing down on top of them. Justin came to Maia's rescue and tossed McGrew away into the moat. Outside the cave - Justin picked Maia up and cradled her as he sobbed. He kisses her. While not noticing - the Stone glows bright and then fades to a deep red as the marks fade away. Maia awakes and they were both very happy to be together. It got even better.
It turned out, while they were at NIMH, Arthur had managed to swipe a syringe containing the same serum that Dr. Schultz had used on Jonathan, and the other mice and rats, increasing their intelligence and longevity. Mr. Ages taught Arthur how to administer the serum on Mrs. Brisby, and Arthur did. It hurt her, but not for long.
The next day - after Timmy and Martin were brought back home, and Nicodemus was once again the leader of the rats, with Justin as his right-hand man and they had straightened everything out with Nash and Heather - Maia told Justin a secret. She would like to have some more kids and have a husband again. Justin told her the same thing - because he truly loved her. What happened next? They brought forth their first son between them, Jonathan Brisby, Jr. Maia truly realized that life had returned almost to normal for her, and, as usual, that one should never give up even when things seems not to be in one's favor.