Mike struggles with surviving at the edge of society as a rough sleeper in London, dealing with a brutal and indifferent world. After a tense incident lands him in prison, he tries to piece his life back together by entering rehab, looking for work, and attempting to reconnect with people, but he is trapped in a cycle of self-destruction and faces systemic failures that hinder his progress.

Urchin explores mental health by focusing on people who fall between the cracks of society and highlighting the ways in which the system fails them. The story centers on Mike's struggles with self-destruction and his attempts to recover, portraying raw and absurd patterns that keep pulling him back, reflecting the complexities of mental health challenges.

The film is set in London and uses the urban environment to emphasize Mike's rough sleeping and marginalization. The city's harsh and indifferent atmosphere underscores the brutal reality Mike faces daily, reinforcing the themes of survival and societal neglect.

Besides Mike, played by Frank Dillane, the cast includes Megan Northam, Amr Waked, Karyna Khymchuk, and Shonagh Marie. These characters interact with Mike as he attempts to rebuild his life, representing various facets of his social environment and the challenges he encounters, though specific character roles beyond Mike are not detailed in the available information.

Urchin portrays Mike as trapped in a cycle of self-destruction, showing his repeated struggles to escape his circumstances. The film presents raw and absurd patterns that pull him back despite his efforts to change, such as entering rehab and seeking work, illustrating the difficulty of breaking free from entrenched behaviors and systemic obstacles.