wild goose chase
a wild or absurd search for sth．nonexistent or unobtainable毫无希望的乱跑；无意义地从事或追求
They embarked on a wild goose chase across the city in a vain attempt to find their lost son．他们在全城徒劳地奔波，无法找到失踪的孩子。
The reporter was sent on a wild goose chase for the man he was to interview had never really existed．那个被采访的人根本不存在，所以被派去采访的记者是在瞎折腾。