There are other ways to open this door. They'll be swabbing the decks with your innards when we're done with you!
~ Allan to Tintin
Allan is the secondary antagonist of the 2011 film The Adventures of Tintin: The Secret of the Unicorn. He served as the first mate of Captain Archibald Haddock, but later turned against him in favor for the infamous collector Ivan Ivanovitch Sakharine.
Allan first appeared at the apartment of the famed journalist Tintin, who is working on the story of Sir Francis' treasure of the sunken ship known as the Unicorn. As it turns out, Allan and the rest of the crew (including Tom and Pedro) are aware of the story and have mutinied against Haddock in order to help Sakharine steal the treasure and avenge his ancestor Red Rackham (who was killed in a failed attempt to steal Sir Francis' treasure). To that end, Allan kidnapped Tintin by putting him in a cargo box and transporting him to Haddock's ship called the SS Karaboudjan, even after murdering Interpol agent Barnaby Dawes (who tried to warn Tintin about Sakharine's intentions).
Allan and Tom searched through Tintin to find the second scroll detailing the location of the treasure (as Sakharine already obtained the first scroll), but is nowhere to be found (since the second scroll is inside Tintin's wallet, which has been stolen by Aristides Silk). As such, Sakharine orders Allan and the crew to kill Tintin as he is no use, but Tintin escapes with the help from his dog Snowy and Haddock. As Tintin, Haddock and Snowy escape on a boat, Sakharine soon learns that they're heading to Bagghar (the location of the third scroll), so he angrily orders Allan and the crew to track them down.
After reaching Bagghar, Allan and Tom spotted Haddock retrieving the first scroll from Detectives Thomson and Thompson (who managed to retrieve Tintin's wallet after arresting Silk). To that end, Allan knocks out Haddock with a bottle of rum before stealing the first scroll just as Sakharine sends his pet falcon to steal the third scroll from a bulletproof glass case. Eventually, Snowy was able to retrieve the first and second scrolls for Tintin, who eventually managed to catch the falcon with the third scroll. However, Sakharine forced Tintin to surrender all three scrolls by pushing both Haddock and Snowy into the water, forcing Tintin to rescue them while Sakharine and his thugs sail away with all three scrolls.
However, Tintin and Haddock were able to pinpoint Sakharine's current location, which happens to be the same dock where Tintin was captured and taken to. With that in mind, the duo and the police were able to set up a trap against Sakharine and his thugs, and Allan ends up being thrown into a cargo truck by Haddock in a failed attempt to rescue Sakharine.
It can be implied that Allan is arrested and sent to prison along with Sakharine and the other thugs for their crimes.