The first USS Mystery (SP-428) was an armed motorboat that served in the United States Navy as a patrol vessel from 1917 to 1919.

Mystery was built in 1917 by Luders Marine Construction Company at Stamford, Connecticut, as a private motorboat of the same name.

Her design was similar to one prepared in 1916 by Luders Marine for a Navy patrol boat, and it is likely that her owner, Mr. Ralph Pulitzer of New York City, intended from the first to make her available to the U.S. Navy in the event the United States entered World War I.

On 18 June 1917, the U.S. Navy acquired Mystery for World War I service under a free lease from Pulitzer, and she was enrolled in the Naval Coast Defense Reserve.

The last few months of her career overlapped with that of the second USS Mystery (ID-2744).