On a beautiful spring morning in Washington, D.C., a high-profile attorney is found dead in his office. McDermott "Mac" Burke and Oliver Shaw, homicide investigators for the Metropolitan Police Department, are called to investigate. There appear to be no signs of foul play, but there is also no obvious sign of a natural cause of death. The detectives are perplexed until the medical examiner notices a tiny pin prick on the lawyer's neck and theorizes that the man was injected with succinylcholine--aka "sux"--which is a common horse tranquilizer that dissipates quickly in the body. As Mac and Oliver begin to look further, they discover that the lawyer had sold his life insurance policy to a large viatical company. Then, they realize that more deaths under mysterious circumstances have occurred among those who've sold their policies to the same company. With mere coincidence seeming unlikely, Mac and Oliver dive headfirst into a now complex and far-reaching murder investigation--if they don't uncover what's really happening, many more lives could be at stake.