Karate instructor Tony Bushby tricked promising art student Katy Wynter into going out with him by using fake Facebook friends and, once he had won her trust, stabbed her to death in a sexually motivated attack.

A gang of 20 high-achieving students attacked 15-year-old Sofyen Belamouadden with Samurai swords and kitchen knives in front of horrified rush hour commuters, leading to what is believed to be the largest joint enterprise murder investigation in British legal history.

This episode features the case of two 15-year-olds who carried out a vicious hate crime.

Leah Green hopes to discover the signs of domestic abuse as she examines the case of 16-year-old Joshua Davies, who murdered his 15-year-old girlfriend Rebecca Aylward.

Leah Green investigates the case of teenagers Hatice Can and Oluwakemi Ajose, who were convicted of the manslaughter of Rosimeiri Boxall in 2009.

Stuart Harling was obsessed with an ultra-violent video game, and in 2006 he stabbed nurse Cheryl Moss 70 times. Steven Miles watched nothing but 'Dexter', and in 2014 he dismembered his girlfriend. Aaron Roach Bridgeman speaks to family members, barrister, journalists and experts who were associated with the cases.