Smoke and fire source detection system, comprising: a flexible printed circuit board with a film substrate and an electrical conductor layer formed on the film substrate, which comprises a two-dimensional conductor path pattern in the plane of the electrical conductor layer, wherein the flexible printed circuit board comprises: a first end portion with an electronic control device and a data and energy supply interface coupled to the electronic control device; a second end portion with an earth connection; a data and energy supply conductor path formed in the electrical conductor layer which runs between the data and energy supply interface of the first end portion and the earth connection of the second end portion; and one or more sensor module portions (12a; 12b; 12c) which are arranged at different longitudinal extension positions along the flexible printed circuit board between the first end portion and the second end portion and which each comprise at least one temperature sensor and/or a smoke detector, and characterised in that at least one of the one or more sensor module portions (12a; 12b; 12c) has a temperature sensor with a plurality of cascaded temperature sensor elements having different temperature threshold values above which the sensor elements are triggered which is then communicated to the electronic control device. a flexible printed circuit board with a film substrate and an electrical conductor layer formed on the film substrate, which comprises a two-dimensional conductor path pattern in the plane of the electrical conductor layer, wherein the flexible printed circuit board comprises: a first end portion with an electronic control device and a data and energy supply interface coupled to the electronic control device; a second end portion with an earth connection; a data and energy supply conductor path formed in the electrical conductor layer which runs between the data and energy supply interface of the first end portion and the earth connection of the second end portion; and one or more sensor module portions (12a; 12b; 12c) which are arranged at different longitudinal extension positions along the flexible printed circuit board between the first end portion and the second end portion and which each comprise at least one temperature sensor and/or a smoke detector, and characterised in that at least one of the one or more sensor module portions (12a; 12b; 12c) has a temperature sensor with a plurality of cascaded temperature sensor elements having different temperature threshold values above which the sensor elements are triggered which is then communicated to the electronic control device. a first end portion with an electronic control device and a data and energy supply interface coupled to the electronic control device; a second end portion with an earth connection; a data and energy supply conductor path formed in the electrical conductor layer which runs between the data and energy supply interface of the first end portion and the earth connection of the second end portion; and one or more sensor module portions (12a; 12b; 12c) which are arranged at different longitudinal extension positions along the flexible printed circuit board between the first end portion and the second end portion and which each comprise at least one temperature sensor and/or a smoke detector, and characterised in that at least one of the one or more sensor module portions (12a; 12b; 12c) has a temperature sensor with a plurality of cascaded temperature sensor elements having different temperature threshold values above which the sensor elements are triggered which is then communicated to the electronic control device.