A cyber BDSM couple; virtual love; a life upended.

Online, any of us can become judge, jury and executioner. But in this ever-shifting digital world, how do we draw the line between the rule of law, and a digital lynch mob? In this episode, an amateur sleuth seeks justice in the case of a young woman's mysterious death - only to discover that the accused killer is the real victim. Elsewhere, a digital activist takes a stand for social justice then finds himself forced to choose between prison and exile.

Our lives revolve around money. But a new world order is emerging, one with the power to create currency and bypass governments and regulation. In this episode, enter the world of digital money: from the recesses of the dark net marketplace to workers in China excavating a new form of money; to 'bitcoin miners' struggling to cope with a potentially volatile algorithm; to a young cam worker whose sexual fetishes link them all together.

The internet was hailed for democratizing ideas. But it is also an arena where conspiracy theories and polarizing echo chambers thrive. In this episode, meet an Alt-Right organizer who's using his social network to urge online sympathizers to join his real world rebellion; the desperate parents of a 17-year-old girl, brainwashed into posting White Nationalist YouTube videos; plus, an American-born former Al-Qaeda recruiter who's had a prolific effect on support for jihad.

Our face is our most distinguishable feature. But to machines, our face is data and it's being transformed into a faceprint in somebody else's database. In this episode, meet a man whose life was ruined after facial recognition technology tied him to a crime he didn't commit; a father who's wired his home with face recognition technology to keep his autistic daughter safe; plus, exclusive access to the FBI Biometric Technology Center, where over half of American's biometrics have been uploaded into a database.

The digital era offers us new technologies to protect ourselves, but are these devices defending our homes or making them more vulnerable? In this episode meet a woman whose home is invaded by a Ratter, a digital stalker who gains entry through her laptop; enter a neighborhood where residents are battling over proposed camera surveillance to monitor everyone's coming and goings; and a sex offender who received the ultimate punishment for invading his victims' privacy - life under constant surveillance.

Communities are the bedrock of society - physical spaces where residents share a collective purpose and common goals. But the internet has given rise to a new kind of community where lies and hate can flourish. In this episode meet a would-be utopia in Spain where civic life is managed on Twitter; a teacher who becomes the target of a digital lynch mob; and the father of a school shooting victim who must prove to the internet that his son existed.

Humans are social beings - but what happens when the emotional bonds that bind us together are threatened by forces we cannot see or touch, or worse, replaced entirely by the network? In this episode, meet a woman who has programmed her dead friend into a chat bot so he can live on forever; a Japanese family who has adopted a childlike AI robot as a member of their tribe; and a desperate mom turning to spyware to track her teenager's every move. Season finale.

Rapid technological advancements are allowing machines to divine the inner workings of our minds like never before. Now that we have given the machines the keys to our mind, what happens next? In this episode, meet Harmony, the world's first artificially intelligent sex robot; a woman who spends her days and nights uploading her mind to the algorithm; and a family whose lives were torn apart by over a decade of war - only to be saved by virtual reality.

Mom's RFID chip; swapping an eye for a camera; "world most connected man."

Online cults; Electromagnetic Hypersensitivity; a quadriplegic's robotics.

Porn addiction; autistic technologists; cognition-enhancing supplements.

Cyberbanging; bloggers turn the tables on trolls; Abdullah X.

Reporting abuse; discovering new worlds; building guns.

Content moderators; the prison of the unplugged; blackhat hacker.

Children forced to perform on camera; revealing the roots of pedophilia.