like a thief in the night
US /laɪk ə θiːf ɪn ðə naɪt/
UK /laɪk ə θiːf ɪn ðə naɪt/
1.
unexpectedly and without warning, often with negative connotations of stealth or sudden departure
:
•
He left like a thief in the night, owing everyone money.
•
The storm arrived like a thief in the night, catching everyone off guard.