James Kincaid controls the local water supply and plans to do away with the other ranchers. Government agent Sandy Saunders arrives undercover to investigate Kincaid's land swindle scheme, and win the heart of one of his victims, Fay Denton.
Beasley, who is after Gayner's land, plans to kidnap his daughter. But Dale overhears their plan and kidnaps her himself. When Gayner arrives to retrieve his daughter, Beasley kills him and makes the Sheriff arrest Dale for the murder.
Mary Brooks' father, who has been studying ancient tribes, falls into the hands of "the people of Zar, god of the Emerald Fingers." Tarzan helps Mary locate her father, rescues everyone from the High Priest of Zar, and takes Mary to his cave.
Rival newspaper reporters Pat Morgan and Ted Rand find themselves unraveling the mystery behind the death of a millionaire philanthropist who fell from his penthouse balcony. When it is discovered that the plunge was not an accident, the building's residents come under suspicion. Soon, the body count begins to mount as three more murders occur by strangulation.
When legendary hunter Bob Rainsford is shipwrecked on the perilous reefs surrounding a mysterious island, he finds himself the guest of the reclusive and eccentric Count Zaroff. While he is very gracious at first, Zaroff eventually forces Rainsford and two other shipwreck survivors, brother and sister Eve and Martin Towbridge, to participate in a sadistic game of cat and mouse in which they are the prey and he is the hunter.
Canadian Mountie Mason is sent south of the border to look for a horse thief with only a watch chain for evidence. He befriends young Andy and when Calhoun hits Andy, Mason and Calhoun fight. In the scuffle Calhoun's watch with the missing chain is dislodged. Mason then sets out to bring in Calhoun and his gang.
Jim Gray is looking for the gang leader known as the General. When Neil Denham is murdered, Jim assumes his identity. He and his pal Squint Saunders then try to join the gang. But they get captured and Jim is told he can join up only if he kills his friend.
Heading west, Ken and Bouncer end up at the Brooks ranch where Ken is to ride Tarzan in the big race. But both the Sheriff and Edmonds are after him and he must hide both himself and the horse until race time.
A crooked lawyer trying to cheat a young girl out of her inheritance tries to convince a sea captain to help him. Re-released in 1939 as "Phantom Submarine U-67."
Clint Belmet (Gary Cooper) is a bit of a firebrand and is sentenced to at least 30 days in jail, but his partners, Bill Jackson (Ernest Torrence) and Jim Bridger (Tully Marshall) talk a sympathetic Frenchwoman named Felice (Lili Damita) into telling the bumbling, drunken marshal that Clint had married her the previous night. Clint is released so he can accompany Felice on the wagon train heading west to California.
The south sea island Tonga is full of plantations and scoundrels. Ellen Bradford arrives expecting marriage to respectable and successful plantation owner only to find he is a drunk and gambler. Being the only white woman she is the desire of scoundrels and cut-throats.