Dr. Mellor is attacked by a masked assailant carrying a syringe full of lethal drugs. Dr Mellor points the finger at rival doctor Thomas Finn, but Finn has an alibi. Dr Mellor is found dead the next day. Finn again has a cast-iron alibi.
Lægen Mellor overlever lige akkurat et mordforsøg. Han beskylder sin kollega og rival Thomas Finn for at stå bag, men Finn har et skudsikkert alibi. Taggartholdet kaster sig over sagen, der udvikler sig særdeles dramatisk.
