Telltale have teamed up with Aardman Animations to give away a full free episode of Wallace & Gromit’s Grand Adventures this week to celebrate the duo’s 20th anniversary.

The episode being offered is the third in the series, Muzzled!, in which con man Monty Muzzle tries to trick the inhabitants of West Wallaby street by staging a fraudulent fundraiser for a local dog shelter. Gromit knows his his intentions aren’t genuine, however, so it’s up to him to save the day.

That isn’t the only good news for Wallace & Gromit fans, all four episodes will be available for the first time on Xbox LIVE Arcade starting today, at a cost of 800 Microsoft Points each.

Telltale is also now accepting orders for the Grand Adventures Collector’s DVD, which features all the episodes, behind the scenes videos and a gallery from the making of the game. As before, the cost to those who already ordered the season’s downloads is just the price of shipping.

For those who haven’t yet played the games, this week the full season is on sale for $20, and donations from each sale will go to the Wallace & Gromit Children's Foundation and Penny Arcade's Child's Play charities.

The free episode can be downloaded directly from Telltale until November 9th.