Up sh*t creek...

megajoltman said
Ummm

All drains in your home eventually lead into your main sewer line, which connects to a city sewer line or a septic tank. Every plumbing fixture including floor drains have a trap. The purpose of a trap is to prevent foul-smelling sewer gas from coming back in to the house.

Agreed Roger, all drains tie into the main line.

65cuda360 said
Drill many holes in the plug, chisel and beat and break out the plug! Clean out the threads and replace with a $2 PVC plug.

this should work, or a rubber bung...kinda like the "universal frost plugs" for engines that you "tighten up"

Have you talked to the neighbours?? Maybe they have a similar problem? If so it might not even be "your problem". Wtih all municipalities I have worked for, it is the home owners responsibility to the curbstop for water, and the property line for wastewater.
Plug could be down stream from your "responsibility"

Good luck.