The Old Man's Friend by Andrew Puckett
Dr Fraser Callan goes to work in a community hospital for older patients. The hospital seems at first to be a model of excellence, but then Fraser realises that more patients are dying of pneumonia than should be the case. When he raises the matter, he is ridiculed, threatened with the sack and finally beaten up by gangs of thugs. Then, after the suspicious death of an old man with terminal cancer, Fraser realises he must act. He reports his suspicions and is persuaded by Marcus Evans, a mysterious civil servant, to work undercover to find the killer. Now his worries are just about to begin.