Suppose there was a world on which evolution and natural selection took an odd turn and never produced an organism that could be considered a plant by our modern definition, but which still produces viable organisms for that world's ecosystem.
While there theoretically are alternatives to photosynthesis as the basis of a food chain, is it reasonable to believe that life will find a way to create a complete and self-sustaining food chain without plants to support it?
For extra credit, provide a brief depiction of how the food chain would work, including what the foundation organism(s) is and how it provides the necessary energy to the rest of the food chain.
It occurs to me that oceanic food chains are dependent on phytoplankton, rather than plants. So, for the sake of argument, please restrict your answers to non-oceanic environments.
To address the duplicate suggestion:
The question What kind of animal... does not solve this problem because that question begins with the assumption that life already exists and includes a means for humans to keep and use an animal as a primary food source. This question challenges the premise that any stable food chain can exist at all with the absence of plants. Additionally, no assumption is made here than the ecosystem would be anything akin to what is found on Earth or that would produce humans or allow them to survive.