"Dragonsfield," apart from being the final lost episode from season one, marked the only solo adventure for Steed prior to the second season. A government research institute attempting to create material guarding against radiation finds one of its staff irradiated by an unknown assailant. Steed arrives and meets the project head Reddington (Ronald Leigh Hunt, later seen in "The Cybernauts"), assistants Susan Summers (Barbara Shelley, later seen in "From Venus with Love") and Lisa Strauss (Sylva Langova, later seen in "The Mauritius Penny"), plus security chief Saunders (Alfred Burke, later seen in "The Mauritius Penny" and "The Girl from Auntie"), the latter sharing his suspicions with Steed. Another scientist survives a brutal assault, Steed no closer to finding the culprit until Saunders decides to set up a meeting to ingratiate himself with foreign agent Boris (Steven Scott, second of three, previously seen in "One for the Mortuary"). This was the only appearance of Eric Dodson (previously seen as a different character in "The Yellow Needle") in the role of One-Fifteen, in place of Steed's regular superior One-Ten, played in exactly ten episodes by Douglas Muir (returning five times next season). Other series veterans present include Herbert Nelson (first of three), Morris Perry (second of three, previously seen in "Tunnel of Fear"), and Michael Robbins (second of four, previously seen in "Square Root of Evil"). Steed would receive sole billing for the initial three entries shot for season two (opposite a new doctor played by Jon Rollason), prior to the introduction of new female partner Cathy Gale, in the capable judo kicking person of Honor Blackman.