The Menoptra attack the Carsinome and the Doctor and his friends come face-to-face with the Animus. The Isop-Top device is their only hope of destroying the alien creature.

The Master is in league with the Axons who intend to consume Earth. The Doctor subjects Axonite to tests and discovers the terrible truth.

Freema Agyeman is best known for playing Martha Jones, companion of the Tenth Doctor.

She attended Our Lady's Convent RC High School, a Catholic school in Stamford Hill and during the summer of 1996 she studied at the Anna Scher Theatre School in Islington. She studied performing arts and drama at Middlesex University.

She played the character of Lola Wise in the revived series of ITV soap opera Crossroads and had small guest roles in other TV series such as Casualty, Mile High and The Bill, in which she appeared in on two occasions as two separate characters. In 2005, she played Mary Ogden, a scene of crime officer, in an episode of Silent Witness. She starred as the character Nana in the independent film Rulers and Dealers, written and directed by Stephen Lloyd Jackson

In 2006 Agyeman was cast as Adeola Oshodi, in the "Army of Ghosts". Her performance impressed the production team who called her back as a serious candidate for the new companion. Following a screen-test with the Tenth Doctor actor, David Tennant, Agyeman was confirmed to the press as new companion Martha Jones on 5 July 2006.

Despite her character's departure from the TARDIS in the 2007 season finale "Last of the Time Lords", Agyeman returned as Martha in series 4 for five episodes. She guest-presented Blue Peter on 24 June 2008 to promote the Doctor Who finale.

Agyeman appeared in three episodes of series 2 of Doctor Who spin off Torchwood. She also had a starring role in the Torchwood radio play, Lost Souls, broadcast on BBC Radio Four to promote the turning on of the Large Hadron Collider at the CERN research facility.

Agyeman appeared several times on The Bedtime Hour on CBeebies reading the story broadcast shortly before 7pm. She narrated the first series of BBC Three's hospital documentary series Bizarre ER,

Since 2009 she has starred as crown prosecutor Alesha Phillips in Law & Order: UK, a spin-off from the popular US Law & Order franchise. 

Marc Warren  is an English actor, known for his British television roles as Danny Blue in Hustle, Dougie Raymond in The Vice and Dominic Foy in State of Play.

In June 2006 he played the character Elton Pope in an episode of Doctor Who titled "Love & Monsters".

Steve McFadden is best known for his role as Phil Mitchell in Eastenders.

John de Lancie is an American actor. 

He has been active in screen and television roles since 1977, though he is best known for his recurring role as Q on the various Star Trek series and as Frank Simmons in Stargate SG-1.

He played Allen Shapiro in the Torchwood stories End of the Road, The Gathering and The Blood Line.

Howard Lang was a British actor best known for playing Captain William Baines in the BBC drama The Onedin Line. 

He served for seven years in the Royal Navy during World War II.

Lang's other parts included roles in The Six Wives of Henry VIII (1970), Z-Cars, Softly, Softly and The Vise.

He played caveman Horg in first Doctor Who story, An Unearthly Child.

He also played the role of Bert Hudd in the first production of Harold Pinter's first play,The Room.