He jumps out of their Bathtub and challenges Jack to their first battle. He hits Barrel on the head with his plunger when he accidentally reveals their plans. When ordered to bring the town back into order, he asks why they would do such a thing. He and the others make their first appearance to Jack in the Cemetery, where he tells him "welcome home", then lies to him about having any involvement with Boogie's resurrection. Lock makes an appearance in the sequel video game, "Oogie's Revenge", where he first joins Shock and Barrel outside of Finklestein's Lab to plot on reviving Oogie Boogie. The Nightmare Before Christmas: Oogie's Revenge They are later shown playing in the snow and even throw a snowball at Jack, to which Lock hides and laughs with Shock and Barrel, thus being his last appearance in the movie.
In the ending of the movie, Lock and the others accompany the ride back to town on top of the Mayor's car, waving to the Halloween Town citizens. They lead him to Oogie's Lair and are by the Mayor's side when they drop a ladder down to get Jack and Sally. When Jack finds them and scares them off, he scurries along with Barrel and Shock to alarm the Mayor that Jack isn't dead and he's still alive. In a deleted scene, it is shown that Lock and the others gather popcorn to watch Oogie Boogie kill Santa Claus and Sally. He helps Shock and Barrel shove him down the pipe into Oogie's Lair, and laugh after hearing him get taunted by Boogie. When Jack expresses his approval and tells them to ensure "Sandy Claws" is comfortable, it is Lock who decides to bring him to Oogie Boogie, insisting that it's the most comfortable place for him.
Lock and his fellow Trick-or-Treaters are more successful with their second attempt on kidnapping "Sandy Claws". They are then told by Jack to take the frightened Holiday Leader back to his own world, which they promise to do. When Shock chokes him, he lunges at her and attempts to throw a few punches at her. When Jack shows them the shape of the Christmas tree door they were supposed to go through, Lock quickly looks over at his cohorts and plays with his hands guiltily, highly implying that it was him who mistook the Easter door for the Christmas one. However, they mistakenly kidnap the Easter Bunny instead. Lock makes another appearance with Shock and Barrel again with their first try of kidnapping "Sandy Claws". In their song, Kidnap the Sandy Claws, he suggests boiling "Sandy Claws" alive and buttering him up, then later shoots Barrel out from their cannon after demonstrating that " Sandy Claws will be no more!” The three then leave for their treehouse, and Lock says that he wants to kidnap "Sandy Claws" before they all agree to do it together. He then says ''wouldn't dream of it jack'' but crosses his fingers behind his back, like Shock and Barrel. After being told their task, he is the first one who tries to leave until Jack pulls him back by the tail, bringing up to his face and strictly warning him and the others to " leave that no-good Oogie Boogie out of this". Lock is first introduced when Jack Skellington summons him and his cohorts for their Christmas assignment of kidnapping " Sandy Claws".
However, he shares the same twisted and morbid ideas as Shock and Barrel do. He sulks after being told to shut up, and retorts with " make me!". When Shock says she " wishes her cohorts weren't so dumb", Lock is the one to tell barrel, who gets insulted and says “I’m not the dumb one” lock comes back and says he's no fun.
Lock often quarrels with the other two Trick-or-Treaters and does not like it when he use being offended or disrespected. 3 The Nightmare Before Christmas: Oogie's Revenge.