Some productions -- even the good ones -- come and go, and you're ready to move on to the next. But some productions grab hold and don't let go. Kenneth Lonergan's Lobby Hero is overwritten, and parts of the Rep Studio production were overacted. But both the play and the production continue to haunt the memory. And in the end memories are all that theater leaves us. This story about four disenfranchised loners is a superbly constructed conundrum with nearly as many twists as a Hitchcock thriller. The Rep production featured some fine performances: Jim Butz as the charming (if verbose) security guard; Lou Sumrall, who turned a one-note police officer into a riveting viper. Then there was a truly affecting portrayal by Tarah Flanagan, whose pathetic, valiant rookie cop was the stage equivalent of an x-ray, so unsparingly did Flanagan expose her character's simple-minded complexities. With reality so up-close and in-your-face, no wonder Lobby Hero is hard to shake.