R.L. Stine 
Fright Knight [EPUB ebook] 

Mike loves hanging out in his fathers weird little museum on Fear Street. Its full of cool stuff a guillotine, a mummy, a bunch of spooky wax figures. Mikes favorite is a suit of armor. At least it was his favorite until he saw a pair of glowing eyes inside the helmet. Until the knight lifted its arm and pointed its sword at Mikes chest. Until the knight challenged Mike to a battle. A battle to the death. Now hes a living knightmare…