Deadly Designs is the fourth mission in Return to Castle Wolfenstein. The OSA has tracked down Deathshead to his Secret Weapons Facility (SWF) hidden beneath the town of Kugelstadt. The town itself is undergoing intense Allied bombing, which creates a good opportunity to infiltrate it. B.J. Blazkowicz enters the town with the help of Kreisau Circle agents and their captured tank. He assists in the defection of a SWF scientist and then proceeds to a bombed weapons factory, from where he obtains a detailed Venom Gun Project Book.