A young heiress of an American gun factory is threatened by a masked man after her father was murdered. This criminal might be a member of her family or a German agent, who wants to get information about the factory's products, perhaps his mystery has a combined solution - we will probably never know...

It is the Christmas Holidays and reformed thief, Boston Blackie goes to Castle Theater to pick up players who will perform for prisoners that are still in prison. He takes a girl with him who has a brother already in prison. She has visited the prison twice in the month, so is not suppose to visit again. However when the group is completed the girl is included as well as Inspector Farrady. One of the clowns in the show is kidnapped and replaced by a con who wants to get even with two ex-partners. Boston Blackie figures out that a con has replaced one of his clowns but is unable to stop him. Blackie's clothes are stolen and a murder is committed. Of course, the Inspector immediately suspects Blackie of being involved. Now it is Blackie's job to find the killer, exonerate himself and help the girl free her brother.

Reporter Frank Sloan, investigating the disappearance of a Chinese slave girl in Chinatown which leads to opium addiction, job loss, and personal ruin, until a major murder brings him back into the story, revealing the dark underbelly of the district.

This whodunit bears no relation to the 1918 picture of the same name, but both films coincidentally had the same director, Tom Terriss. When sleazy theatrical agent Maurice Beiner (Arthur Donaldson) is found stabbed to death in his office, just about everybody is a suspect -- there's aspiring actress Clancy Deane (Eileen Huban), who was one of the last people to see him alive, and Sophie Carey (Alma Rubens) who knows he has some love letters she wrote to Judge Walbrough (George MacQuarrie) before she married her alcoholic husband, Don (Henry Sedley). Or is it Marc Weber (Norman Kerry), who had a falling out with Beiner, or Weber's devoted wife, Fay (Ethel Duray)?

Pursued by three Indian priests after stealing “The Moonstone” a valuable diamond from the eye of an Indian idol Englishman, Hearncastle is found drowned, presumably by the Indians. Possession of the Moonstone passes to his friend Franklin Blake who presents the diamond to his fiancée. However it is stolen and suspicion falls on another girl who loves Blake particularly after she leaves a mysterious note at her suicide. Subsequently, a doctor discovers that Blake walks in his sleep and took the diamond himself while in that state, but then stolen and never recovered. At last, the thief confesses before his death with Blake and his fiancée reuniting.

A mad scramble for stolen loot ensues after Boston Blackie has prisoners released for work in a wartime defence plant.

Boston Blackie, in the 11th film of the Columbia series, indulges in some wit-trading with a squirmy spiritualist who deals in blackmail, murder and the occult. "Blackie" out to help his pal, "Runt," recover some jewels, finds himself involved in the homicides, and also finds himself as the prime suspect, and now has to find the real culprit in order to clear himself. So "Blackie,", a man of many talents and already a proved magician from cases past, shows he knows a little bit about dancing skeletons, walking phantoms and spiritualism himself, and holds a séance to unmask the murderer.

Heavyweight boxing champion Jack Dempsey stars in this 15 chapter action serial, of which portions of reels 1, 2, and 4 survive. In the serial he plays the star fullback of his college's football team who gets drawn into an adventure when he stops to rescue a young woman from some thugs on a country road. It includes a gag featuring an exploding football. The rest of the cast includes Lon Chaney, Edgar Kennedy, Bull Montana, Josie Sedgwick and Herschel Mayall.

After a rare gem is stolen from an exhibition at a posh hotel, Inspector Farraday decides to recruit former thief Boston Blackie to find the stone. Along with his assistant, "The Runt", Blackie focuses his investigation on the hotel manager, George Daley, and his sister, Eileen. Through disguises and ruses, Blackie and the Runt try to trick their way to discovering the thieves.

Blackie is the natural suspect when an expensive pearl necklace is stolen while he is supposed to be guarding it.

Blackie is arrested when retrieving stolen gems from a safety deposit box for a friend.

Blackie helps the police rescue hostage from an escaped maniac on a killing spree.