|“||In a few minutes, we'll be on our private jet to Costa Rica! Here's to me!||„|
|~ Claudia tempting fate at her apparent victory.|
|“||Here's to you, Claudia.||„|
|~ Klaus sarcastically toasting his sister as they are arrested.|
Klaus Furschtein is the secondary antagonist of the 1987 cartoon film The Chipmunk Adventure, the main antagonist being his sister, Claudia. He and his sister are the co-leaders of a global, German-led diamond smuggling ring who are desperate and determined to have them delivered with as much concealment as possible as all of their previous attempts under Klaus' supervision have been met with failure thanks to INTERPOL (International Criminal Police Organization), led out of their Los Angeles Division office by Inspector Jamal.
He was voiced by Anthony De Longis, who also played Blade in the 1987 film Masters of the Universe, Culluh on Star Trek: Voyager, voiced the character Zygon in the 1985 animated film Starchaser: The Legend of Orin, Mick Cutler in the 2011 video game Resistance 3.
Klaus and Claudia tricked the Chipmunks and Chipettes into aiding them in smuggling diamonds across the world under the guise of a hot-air balloon race across the world, taking advantage of an argument between Alvin and Brittany after playing an arcade game based on the novel Around the World In Thirty Days. Klaus pretended to side with the Chipettes, whilst Claudia pretended to side with the Chipmunks.
Klaus and Claudia gave each team (Chipmunks and Chipettes, respectively) small dolls in their images that they were to place at each location at which they arrived and exchange for dolls in the opposing teams' images as proof of their travels. The first team to arrive back at the starting point would win the race and be rewarded with a cash prize of $100,000.
What the Chipmunks and Chipettes didn't know was that each doll was actually stuffed with diamonds, and that they would be exchanged for dolls containing money (that was likely being used by clients to pay for the diamonds). Thus, they agreed to the terms, unaware that they were aiding the smugglers.
However, during their travels, the Chipettes became distracted when they discovered a baby penguin in Egypt and tried to take him back to his family. Upon henchmen of Claudia, who was unaware of this, reporting this to her, she believed that the girls had found the hidden diamonds and were trying to make an escape with them. Thus, when they diverted from their assigned course, Claudia had her henchmen go forth to capture the girls and retrieve the diamonds and money they had already collected.
Claudia's henchmen caught up with the Chipettes as they were delivering the baby penguin to its family in Antarctica. When the thugs tried to take the dolls, the girls fought back, ripping one of the dolls in the process and revealing the diamonds. Luckily, the penguins, grateful to the Chipettes for returning their baby, fought off the thugs with snowballs.
After seeing the diamonds in one of their own dolls, it didn't take long for Brittany, Jeanette, and Eleanor to realize that there could also be something in the Chipmunk dolls. They opened one and found the money being used to pay for the diamonds, and Jeanette realized the true intent behind the "race." Now aware of what was happening, and with Brittany realizing that Alvin and the Chipmunks were in grave danger, as well, the Chipettes headed off to find the Chipmunks, and after rescuing them from Fijian natives intending to sacrifice them to hungry crocodiles, the two groups flew back to Los Angeles, with the Chipettes telling the Chipmunks everything off-screen.
However, when they arrived at the airport, Klaus and Claudia were waiting for them and attempted to kidnap them once Alvin and Brittany revealed they knew all about the plan and would not hand over the diamonds and money willingly. This resulted in a brief chase through the airport that resulted in the Chipmunks and Chipettes temporarily eluding their pursuers. Not wanting to continue the chase out of fear of making a scene in front of so many people at the airport and possibly alerting law enforcement, Claudia thought of a plan to force the children's surrender. She made a false threat of Miss Miller having been kidnapped, which indeed made the Chipmunks and Chipettes agree to Klaus and Claudia's terms. The Chipmunks and Chipettes were forced into a 1935 Rolls-Royce Silver Cloud I and kidnapped by the Furschtein siblings.
At the same time, Dave arrived home to the airport and heard Alvin's cries for help. Inspector Jamal, who had been monitoring Klaus and Claudia very closely for months, ran up, identified himself, and he and Dave began to give chase in his 1987 Chevrolet Caprice patrol car. However, when Claudia sees Jamal's emergency lights behind them, she has her driver run a red light, causing two other cars to crash into each other and block Jamal and Dave off at an intersection, forcing Jamal to stop and deal with it before he could resume the pursuit. While it at first appeared that Klaus and Claudia would escape on a private jet to Costa Rica, and likely take Mario and the six children with them as prisoners to prevent them from telling the authorities about the diamonds, they were accidentally run off the road by none other than Miss Miller, who was heading to the airport to pick up Dave. Klaus and Claudia were then arrested and taken away by Jamal and the police, their smuggling ring now shut down for good.