When called to the scene of a horrendous crime Will sees that the police are not being told the whole truth. His insights into the case attract the interest of Dr. Helen Magnus who introduces him to her sanctuary for 'abnormals,' creatures that have remained hidden from most of the world only appearing occasionally as characters in stories and myths.
When Dr. Magnus, Will and Ashley rescue three entombed women Will struggles to accept that the women are suffering from anything more than a group delusion, Dr. Magnus suspects that the women are much more than they appear.
After thieves make a dramatic escape that baffles police Dr. Magnus suspects an abnormal's involvement. The robbery reminds Will of an old FBI case he could not solve; but this time he will.
After capturing a particularly elusive abnormal the plane carrying Dr. Magnus and Will crashes while transporting the creature. Dr. Magnus and Will soon discover why this abnormal has never been captured before.
Dr. Magnus, Ashley and Will retrieve two species of abnormal that have the ability to camouflage so well that they are near invisible. One appears to be a vicious predator, the other a cute, furry animal but nothing is as it appears.
Henry comes to terms with his abnormal side, Ashley works through her feelings about her parents, and Will helps a young autistic man whose father possibly shot himself.
When an old friend of Will's goes missing his wife contacts him for help. With the help of Helen and Ashley, Will finds that his friend has been taken and forced to fight underground. But as they continue to search, things start to become quite familiar to Helen.
Desperate to get her first exclusive story, a reporter and her cameraman sneak inside an evacuated building. Inside they find Dr. Magnus and her team, and a creature greater than any of them were prepared for.
In an unprecedented alliance Druitt and Sherlock Holmes work with Sanctuary to deduce why normally placid abnormals are running amok. Their plan, infiltrate their prime suspect, The Cabal.
With Ashley and Henry in the hands of the Cabal the rest of the team venture to a remote vampire enclave to recover the last known sample of vampire blood; the power they need to defeat the Cabal.