Is there anyone more formidable than Leonardo, the sword-wielding leader of the TMNT? No one except perhaps his own dark, mirror image. Flashback to the times when Leo was compelled to indulge his most dangerous impulses and become Dark Leo, one of the deadly ranks of the Foot Clan. This special one-shot brings together the most popular and exciting stories from when the leader of the Teenage Mutant Turtles went over to the dark side.