Francesca Simon 
Two Terrible Vikings and Grunt the Berserker 

It's not easy being the WORST at everything!Hack and Whack are the very worst Vikings in the village – until a fierce and stinky berserker moves in – NEXT DOOR!WILL the brand new school help the twins outwit this villain and his vicious dog, Muddy Butt?And will Twisty Pants, Dirty Ulf and Elsa Gold-Hair help vanquish this foul fiend?