Robert Louis Stevenson cherished the 1866 penny dreadful A Mystery in Scarlet, written by his "genuine influence" Malcolm J. Errym, the pseudonym of "Sweeney Todd" creator James Malcolm Rymer (1814-84) and illustrated by the celebrated "Phiz" (Hablot K. Browne, 1815-82). Once assumed lost, A Mystery in Scarlet is now reprinted for the first time since 1866. To shed light on the Victorian experience of serial, multimodal reading of penny dreadfuls, this annotated critical edition reproduces Rymer's text and Phiz's illustrations in their original eighteen-installment format.