What is the ruling on money taken from overtime work in a company where the nature of the work does not necessitate overtime?

If employees staying after working hours is a trick to unlawfully obtain money, then this is forbidden (haram). The wages they receive for overtime hours are forbidden (haram), and they must return them to the company or spend them on public welfare and for those in need. However, if the overtime is at the behest of the supervisor, then there is no blame upon them.