Police try to solve a murder on board an ocean liner.
| Actor | Role |
|---|---|
 Noah BeeryCapt. John Holling | Capt. John Holling |
 Astrid AllwynLila Kane | Lila Kane |
 Edwin MaxwellMajor Pope | Major Pope |
 Gustav von SeyffertitzInspector Von Kessling | Inspector Von Kessling |
 Ralph LewisProf. Grimson | Prof. Grimson |
 Cornelius KeefeFirst Officer Cliff Rogers | First Officer Cliff Rogers |
 Zeffie TilburyGranny Plimpton | Granny Plimpton |
| BBoothe HowardCapt. Downey | Capt. Downey |
 Howard HickmanDr. Howard | Dr. Howard |
| JJerry StewartEdgar Morton | Edgar Morton |
| JJohn M. SullivanWatson | Watson |
 George 'Gabby' HayesJoe, the Watchman | Joe, the Watchman |
 George ClevelandSimms, the Steward | Simms, the Steward |
| RRaymond BrownSpy Chief (uncredited) | Spy Chief (uncredited) |
 Gordon De MainCommander Bryson (uncredited) | Commander Bryson (uncredited) |
 Olaf HyttenGrimson's Aide (uncredited) | Grimson's Aide (uncredited) |
 George NashWaiter (uncredited) | Waiter (uncredited) |
| HHarry SchultzAide (uncredited) | Aide (uncredited) |
 Slim WhitakerCrewman (uncredited) | Crewman (uncredited) |