Dean first appears as the Losers Club is leaving a Chinese restaurant where he comes across a freaked-out Richie and tells him that he’s a huge fan of him.
While he and the others are searching for their childhood items so they can perform the Ritual of Chüd to annihilate It, Bill meets Dean at the storm drain where his brother Georgie was murdered nearly 28 years ago. Dean tells him that he lives at his former house and that he’s been hearing voices coming from the drain. Bill urges Dean to get out of Derry, however, Dean doesn’t heed Bill’s warning.
Dean then goes to the Funland Carnival. Bill, who had just discovered that Pennywise has targeted him via a message on his skateboard, arrives to warn him that he’s in danger. Wandering through a maze of mirrors, Bill frantically searches for Dean, eventually finding him boxed in. Dean gets annoyed by Bill following him. It is then that he notices Pennywise behind another glass wall. Bill then frantically begins pounding on the glass, trying to break it and rescue Dean, to no avail as the glass is considerably strong, while Pennywise headbutts the glass. Dean, meanwhile, finally realizing he’s in mortal danger, desperately tries to find a way out, but has nowhere to run. It’s repeated headbutts cause the glass to start to crack. Grinning evilly, Pennywise smashes through the glass and devours Dean before Bill’s eyes, splattering the wall with the hapless kid’s blood.