Current and previous research works on ways to tackle problems related to future emission requirements of the internal combustion engines have always been mainly on exhaust gas after-treatment, either being a filter or a catalyst device installed at the engine after-exhaust system. From the engineering point of view, however, the exhaust after-treatment is only the second best solution, minimizing of pollutants in the engine itself should be of prime target.A conceptualised new sequential two-stage combustion system is believed to be the solution to many difficulties posed by modern engine requirements. The proposed engine system is designed to handle the main combustion process in a conventional reciprocating engine, and the secondary combustion process in a Wankel-type rotary unit; all processes have to be completed within one fall engine cycle.The major objective of this paper is to discuss the working principle of this new engine system featuring a piston engine with two rotary units arranged at its downstream. This new engine design will also contribute to exploration of other areas of interest like alternative fuels in place of the conventional fuels. A muting feature of the engmie is also described, which opens an explorable area such as application of the internal combustion engines for domestic usage.