Harold is an iceberg... lettuce. (But he doesn't realize the "lettuce" part because part of his sticker has ripped off.) So one day when he sees a documentary about how the icebergs are melting, Harold starts to worry, thinking that he's melting too.

As his anxiety grows and grows, and he tries to find a way to stop melting, his fellow food friends try to help him cool down in a different way.