社交网络带来的网络红人，超高点击率以及关注度让有些人陷入一种奇怪的状态。拍摄视频成为他们生活中的必备品，而简单的事件越来越不够吸引人，为了获得更多人的关注，Balthazar的拍摄事件慢慢让人步入恐怖的情境之中，朋友一个个被杀死，而真相又究竟是什么？两名男生的死亡引起了警方的注意，他们都是被谋杀的，一段由监控拍摄下的画面表明他们曾受到不同程度的欺辱，而监控里的施暴者自然成为了警方怀疑的对象，随着调查的深入，越来越多的疑点浮出水面……

　　It returns six months after the shocking finale of Season 3, and the team must overcome their grief to tackle a dangerous crime wave.　　This time, the gloves are well and truly off for Professor T in his lectures and a new musical pursuit, romance is very much alive for his mother Adelaide Tempest (De la Tour), and the lines between professional and personal become blurred for therapist Helena Goldberg (Stevenson).　　Meanwhile, DI Maiya Goswami (Sunetra Sarker) takes charge of the police force with series favorite DS Dan Winters (White) fiercely at her side.