In Transient Analysis, what happens when free electrons are applied to a matrix of resistors that don't have a ground?
Consider that there is a (probably tiny) parasitic capacitance between each node of the "floating" circuit and the ground terminal of the power supply and whatever it is connected to. Now you can analyze this circuit using the usual concepts of conventional current, charge, and voltage. There's no need to worry about electrons. 

When the supply is first connected, current flows in to the circuit and returns to the supply's anode through the parasitic capacitors. Once sufficient current has flowed, the capacitors will be charged up to 30 V. No further current will flow and the various nodes of the resistor network will remain at 30 V as you expected.