notices a wanted poster for the criminal Feathers McGraw, supposedly a chicken but really the penguin in disguise. Noticing McGraw has been controlling the Techno-Trousers, Gromit begins to follow and spy on him, eventually returning to the house. His research confirms McGraw's identity and uncovers a plot to steal a huge diamond from a local natural history museum. Gromit is detained when one of Wallace's inventions accidentally triggers. McGraw puts a special helmet on the sleeping Wallace's head and uses the remote to march the Techno-Trousers, with Wallace inside, to the museum. Directing the Techno-Trousers into the museum through the air vent, McGraw secures the diamond via a toy crane claw built into the helmet; however, Wallace awakens when a burglar alarm trips. Returning to the house with Wallace, McGraw holds him and Gromit at gunpoint, and attempts to flee with the diamond. An extended chase follows throughout the house atop Wallace's sprawling model train set; Wallace is eventually freed from the Techno-Trousers, and Gromit manages to capture McGraw in a milk bottle. McGraw is returned to his prison cell in the wall of the city zoo, and Wallace pays off all his debts with the reward money, throwing the Techno-Trousers into the rubbish. However, they walk off into the sunset on their own. Soundtrack alterations In the original airing, first VHS release of the film and the 1999 DVD release, Gromit's birthday card plays "Happy Birthday to You". In subsequent home video releases and airings, this was replaced with "For He's a Jolly Good Fellow" to avoid copyright infringements (likely due to this version of Happy Birthday being copyrighted). Also altered (again for reasons of copyright) are two specific songs from the penguin's radio, which were replaced with unidentified pieces of music, played through a Hammond organ. "Tie a Yellow Ribbon Round the Ole Oak Tree", also played through the same instrument, was left intact due to being in the public domain. The pieces that were removed are "Happy Talk" from the musical South Pacific and "(How Much Is) That Doggie in the Window?", along with Wallace's singing of the latter during the subsequent morning. In addition, Gromit's television during breakfast no longer plays the Open University theme, although an announcer can still be heard saying, "Welcome to Open University". However, the original soundtrack can still be heard in the background of the commentary track of the DVD release,