Men from Scotland Yard and military intelligence build a dossier on a sabotage ring.
A bookmaker with a fancy for detective work attempts to prevent the execution of a potentially innocent man.
George is a disaster-prone zoo attendant who accidentally discovers a substance that accelerates motion, enabling his greyhound to run faster. This attracts the interest of a gang of criminals, who kidnap George's dog and plan to substitute their own in an important dog race. George and his friends defeat the crooks and their dog wins the race.
John Ainsworth helps win a rowing race for Sydney University against Melbourne University. While celebrating at a nightclub, he demonstrates his skill with the violin with one of his original compositions. He also flirts with a young woman, Ann Brady, to the displeasure of a crook, Webster. A brawl results and John is expelled from university. John's sheep farmer father – who is disdainful of culture and wants John to marry a rich girl – is furious and disowns his son.
Daubeney Carshott, a concert pianist, leaves London to dive for pearls on Thursday Island in the South Seas at the whim of Stella Raff, his fiancée. Once there, he discovers that the life he leads as a pearl diver is better in every way than his former existence as a social-lion pianist. He meets and falls in love with Lorna Quidley, after learning this Stella had send other suitors off in quest of a giant pearl for her.
After being fired from his job at a grocer, George, gets a job as a stableboy at a local stud farm run by the Fleming family. He befriends the horse Hotspur who is a favourite to win the Melbourne Cup, and develops a strong whistle which is used to make the horse run fast.
William Kell, the keeper of a lighthouse on a lonely stretch of coastline, marries cabaret dancer Eileen. His young wife, however, goes on to have an affair with Henry Cass, the handsome assistant later taken on by her husband; when she then begins to flirt with a stranger who is rescued from the wreck of a motor-launch, a chain of shocking events is set in motion...
When Grace Raymond follows Neil Garth, her hard-drinking fiancé, West, she finds him living in a squalid desert cabin. Forced to choose between being raped by outlaws or giving in to Neil's sexual demands, Grace moves in with her fiancé. A year later, Grace rescues James Stapleton, a gold miner, from a desert death and helps him to escape from Neil's greedy clutches. Before Neil can punish her, she knocks him out and flees to New York, where she meets and then marries Oliver West, a jeweler with failing vision. To help with his medical bills, Grace sells a short story, but Neil shows up and threatens to expose her past unless she gives him her earnings. Eventually, Oliver finds out about Grace and Neil and goes blind from the shock. Determined to win Oliver back, Grace enlists the help of Stapleton, now a rich broker, to thwart Neil and secure a sight-restoring operation for Oliver. When Oliver hears Neil's confession of Grace's difficult past, he finally forgives her.