A scientist discovers a death ray and locks it in a box, giving the key to his daughter, who soon finds herself hunted by criminals looking to steal the deadly mineral.

Adapted from a novel by Larry Evans, Once to Every Man tells the tales of Danny Bolton, a pugnacious, hard-drinking country boy.

After a brief and unhappy marriage, Gladys Dale finds work as the companion to Diana Dorset, the daughter of a society matron. Mrs. Dorset also has a spendthrift son, Robert, who makes a number of unwelcome advances to Gladys. However, with the arrival of Edwin Fairfax, Mrs. Dorset's younger brother, Gladys finds a soul mate. But then Fairfax has to report for duty in France (being as World War I is going on) and he leaves.

Janet Rigsby loves Richard Morgan, a Denver college student, but loses him when he is caught in a fire. Shortly after Richard's presumed demise, Janet leaves her home and bears a son out of wedlock. Over the years, she struggles to make ends meet while raising Bud, her son, on her own. Although her savings are small, Janet manages to send Bud to college. Chastised for his poverty and illegitimate birth, Bud, who is in love with the college gardener's daughter, suffers the ridicule of his peers and eventually comes to blows with and threatens one particular boy for insulting his mother. In the ensuing confrontation, the boy is killed and Bud is arrested for the crime. During the course of the trial, Bud discovers that the district attorney is Richard Morgan, his father. The testimony of one expert witness reveals how the murder in truth was committed, and a liberated Bud happily reunites with his mother and new-found father.

Jack Brookfield, a gambler with clairvoyant and hypnotic powers, is able to win at cards through his unique gift. But when he inadvertently hypnotizes young Clay Thorne, Thorne kills an enemy of Brookfield's while under a trance. No one believes Brookfield's protestations that Thorne is innocent of any murderous intent

Ne'er-do-well Joe Louden scandalizes his small town and especially the proper Judge Pike. But through the love of young Ariel Taber, Joe shows the town who the real scoundrel is.

Claire Martin, niece of the wealthy Mrs. Taylor, suffers from loss of memory. Under the effect of this, Claire acts as an entirely different person. She wanders through the woods seeking shelter and food, and finally reaches a cabin temporarily occupied by a New York sportsman, who is fishing and hunting in the woods.

John Glayde is a stone-hearted man intent on wealth to elevate his family, losing his wife to another man in the process.

Edward Thursfield, chief engineer of the bridge building firm of Henry Killick and Company, is building the largest concrete bridge in the world. Employed in the New York office is a young man named Arnold Faringay. Arnold sees an opportunity of using money from the payroll for a big deal.