in league (with someone)
idiomPart ofleague
in league (with someone) — idiom
1. Working together secretly with another person or group, usually to do something
1.idiom
Definition
Working together secretly with another person or group, usually to do something dishonest or wrong.
Example
The security guard was in league with the thieves who robbed the jewellery shop.
Many people believed that the mayor was in league with local property developers.