Mook is an alien criminal, boasting to be the best thief in the Earth quadrant. He is green skinned, web-footed, and pronounces "sneee" before and after each phrase. He uses his own grammar, like "i's mets" instead of "I met".

A bounty was put on him dead or alive, and bounty hunter Teyst Grifbo captured him in a bar on Sargent Prime and taken to the brig of his ship.

The ship made a stop by Earth where Grifbo captured Daniel Carrington, Joanna Dark and the Maian Elvis. As they were planning their escape, Mook ensured them that nobody can escape from Grifbo and introduced himself. When finally they managed to open the cell door, for some reason he tried to alert Grifbo.

Grifbo tried to stop them on their way to the teleporter but the human female defeated him and damaged the ship before escaping. As Grifbo was recovering from a flash grenade, Mook scorned him and promised that he would tell the bounty hunters guild about his failure. Grifbo opened his cell and reminded him that the reward for him did not want him necessarily alive.