Dead Welsh Kings Are Dust And Shadows

raven boys and infernal devices crossover fanfic, don't ask why...
BLUE, GANSEY, RONAN, ADAM, AND NOAH ARE MAGGIE STIEFVATER'S CHARACTERS
WILL, TESSA, JEM, HENRY, MAGNUS, CHARLOTTE, JESSAMINE, AND BRIDGET ARE CASSANDRA CLARE'S CHARACTERS
NONE OF THE CHARACTERS ARE MY OWN
Ronan dreamt a time machine, which Blue and the boys then decided to use to go back to the time Glendower was still alive, but they didn't enter the time right, so that machine took them to 1878 instead, to the bottom of the London Institute, where Henry's laboratory is located.