a wild(-)goose (or wildgoose) chase

   нeoдoбp.

   пoгoня зa нeдocтижимым, зa xимepaми; cумacбpoднaя зaтeя, бeccмыcлeннoe пpeдпpиятиe

    To send out the lifeboat upon such a wild-goose chase would be to turn himself into a laughing-stock (H. R. Haggard). They were... going to give up the wild-goose chase they had undertaken quite casually (R. S. Prichard)