Why and how does charge flow from one capacitor to another capacitor when the two are connected to each other by a conducting wire ?

I am not being able to understand that why and how does negative charge flow from a capacitor having lower potential difference between its plates to a capacitor having higher potential difference between its plates, when both are connected by a conducting wire.

Also, why is the charge lost by one = charge gained by the other capacitor ?

Please help me understand this with the help of a figure.

Thanks.