Riis introduces the book's three major themes: the consequences of greed, tenements as sources of social ills, and the urgency of reform.

Riis traces the tenement problem to landlords who began partitioning large rooms to maximize rent from newly arrived immigrants after a trade boom.

Riis describes the creation of the Board of Health and the first Tenement House Act as New York's initial formal attempts at tenement reform.

Riis uses an imaginary colored map to illustrate the ethnic patchwork of immigrant communities spread across New York City's tenement districts.

Riis tours Cherry Street and photographs two children outside a once-fashionable mansion that has been converted into an overcrowded downtown tenement.

Riis documents the notorious Mulberry Street Bend across four photographs, revealing violence, extreme overcrowding, and conditions worse than anywhere else in the city.

Riis accompanies police on a raid of stale-beer dives in Mulberry Bend, resulting in the arrest of 275 people on vagrancy charges.

Riis exposes cheap lodging houses where thousands of homeless men sleep nightly on thin fabric cots while politicians notice them only during elections.

Riis examines Chinatown, describing opium dens that seduce young women and characterizing the community as fundamentally resistant to assimilation.

Riis enters Jewtown and finds an endless panorama of tenements, crowded street markets, and synagogues crammed into rear-tenement back rooms.

Riis devotes consecutive chapters to tenement children, documenting boys sleeping on street grates and approximately 25,000 infants abandoned over twenty years.

Riis exposes how alcoholism, street gangs, and crime all grow directly out of the tenements and the desperate conditions they impose on residents.

Riis documents starvation wages paid to New York's working women and warns that poverty drives many toward sex work to survive.

Riis visits Blackwell's Island psychiatric facility and concludes that the hundreds of women confined there are all victims of poverty.

Riis cites landlord Miss Ellen Collins as a model reformer who earns a steady profit while genuinely improving the lives of her tenants.

Jacob Riis opens by establishing that three-fourths of New York City's population lives in tenements created by landlords driven purely by greed. He tours downtown Manhattan's worst neighborhoods, from Cherry Street and the Mulberry Street Bend to Chinatown and Jewtown, documenting deplorable conditions through photographs and vivid description. The book exposes how alcoholism, gangs, crime, child poverty, and the exploitation of working women all flow directly from the tenement system. Riis argues throughout that greed is both the cause and the primary obstacle to reform, and that only a Christian approach to profitable landlordship can solve the crisis. He concludes by presenting Miss Ellen Collins as living proof that a landlord can treat tenants humanely while still earning a reasonable return.

The headline story of New York's tenement crisis and the call for reform.

Riis includes an architectural sketch showing dark rooms outnumbering lit rooms 19 to 12, illustrating the chronic scarcity of light inside tenements.

Riis presents two side-by-side architectural sketches showing that the new ventilation law's air shaft failed to solve the core problem of overcrowding.

Riis documents the Gotham Court tenement, where a cholera epidemic killed 195 out of every 1,000 residents due to extreme overcrowding.

Riis walks through a Cherry Street tenement and finds a child dying of measles while the surrounding family sits in resigned silence.

Riis describes the Italian community as victims of contractor exploitation but acknowledges their honesty and loyalty as genuine redeeming qualities.

Riis photographs the notorious Bandit's Roost alley in the Bend, showing a narrow passage where residents hang out of first-floor windows.

Riis cites the case of a lodging house resident who later fled New York and was shot dead while robbing disaster victims elsewhere.

Riis describes the conviction of criminal David Smith, who forced a 14-year-old runaway boy into daily begging while physically abusing him.

Riis witnesses health officials raiding a Jewish street market, confiscating rotten food while frightened tenants scatter indoors and lock their doors.

Riis visits a Ludlow Street sweatshop and finds entire families sewing garments behind every door from early morning until late at night.

Riis personally enters a saloon after midnight and forbids a bartender from serving alcohol to a young child who has just walked in.

Riis documents the Alley Gang of Poverty Gap, which murdered a boy for the sole offense of trying to earn an honest living.

Riis documents Charity Organization Society records showing over 135,000 families have sought charitable assistance, revealing the extraordinary scale of urban pauperism.

Riis visits the almshouse and finds elderly men and women who have been sent there to die by their own heartless children.

Riis shares architectural sketches from Brooklyn reformer A.T. White as a blueprint showing what a humane and profitable model tenement could look like.

While the main plot pool covers the broad arc, these events focus on the particular scenes and cases that accumulate into damning evidence. From architectural sketches revealing dark rooms outnumbering lit ones, to cholera deaths at Gotham Court and a child dying of measles in a Cherry Street tenement, Riis builds his case detail by detail. He documents specific criminal cases, a market raid scattering terrified tenants, and a Ludlow Street sweatshop where families sew garments from dawn to midnight. The chapters on the Italian quarter, the saloons, the gangs, and the almshouses each contribute distinct human evidence to Riis's central argument about greed. The pool ends with Brooklyn reformer A.T. White's model tenement blueprints, offering a concrete vision for what decent housing could actually look like.

The vivid details and specific scenes that give the tenement crisis its human face.

Riis reveals that three-fourths of New York's population lives in tenements, establishing the housing crisis as one threatening the city's entire social fabric.

Riis concludes his tenement history chapter by warning that the city's wealthy residents risk violent retribution if the housing problem goes unaddressed.

Riis describes how Irish immigrants have risen from tenants to landlords and saloonkeepers, fundamentally reshaping the city's ethnic and economic hierarchy.

Riis observes that one well-managed tenement near the Bend run on Christian principles has a significantly lower mortality rate than its neighbors.

Riis reveals that the owner of three squalid lodging houses earns a fortune annually, proving the tenement crisis is driven by deliberate greed.

Riis photographs a Czech family in their tenement cigar workshop, including a young child rolling tobacco leaves alongside his working parents.

Riis argues that New York's Black community has achieved a form of second freedom by relocating away from the worst downtown tenements.

Riis personally counts 128 children among 40 families in one tenement block before abandoning the count, overwhelmed by the density of child poverty.

Riis argues that even a handful of flowers transforms the faces of tenement boys widely dismissed as savage, proving circumstances shape character.

Riis uses the Marxist term proletariat to describe mistreated tenement children, framing them as potential future revolutionaries if conditions remain unchanged.

Riis reveals that infants retrieved from city streets face a mortality rate near 90%, exposing near-certain death for the city's abandoned babies.

Riis reveals that more than 40% of the city's licensed saloons cluster in the tenement districts, exposing those communities' saturation with alcohol.

Riis recounts a man who randomly slashed strangers on a street corner, using the attack as a warning that far worse violence will follow.

Riis opens his final chapter with eight numbered facts asserting that New York's wage-earners have a fundamental right to decent and affordable housing.

Riis ends the book with a metaphor of a rising sea of millions trapped in tenements threatening to overwhelm a complacent, sleeping city.

These events trace the key moments of revelation and argument that give Riis's book its cumulative moral force. Beginning with the disclosure that three-fourths of New Yorkers live in tenements, Riis builds toward increasingly alarming discoveries: a slumlord's staggering annual fortune, photographs of child labor in Czech sweatshops, and a near-total mortality rate for infants abandoned on city streets. Riis uses these turning points to shift the reader's view of tenement residents from strangers to sympathetic victims whose suffering is entirely a product of systemic greed. The argument reaches a peak through the symbolic transformation wrought by a handful of flowers, the loaded invocation of the word proletariat, and the ominous story of a man randomly attacking strangers in the street. Riis closes with eight direct demands for housing justice followed by a metaphor of a rising sea poised to overwhelm a city that has chosen not to see.

The discoveries and moral turning points that drive Riis's argument toward urgent reform.