wrong scent, on the
On a false trail or track, as in He managed to put the police on the wrong scent and got away. This term alludes to hunting with hounds. [c. 1600]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.