Abstract: A surveillance drone system is provided herein generally including an UAV, a base power station, and, a tether for connecting the UAV to the base power station to provide electrical power to the UAV when airborne. The base power station may include a cable take-up assembly for releasing and taking up the tether. A plug or power module is provided at the free end of the tether configured to be detachably coupled with the UAV, to transmit electrical power to, and, possibly, data to and from, the UAV. With the plug or power module being detached, the UAV is free to fly unrestricted. This arrangement allows for the UAV to be airborne for prolonged periods to allow for monitoring a region and for release to allow the UAV to investigate anomalies in the monitored region.