Our Doctor Who superfan Lizo reviews the fifth episode of the fourth series - The Poison Sky.
It's not looking good. The skies over the world are filling with toxic gas, the evil Martha clone is helping to put the Sontarans' plan into operation, and the Doctor can't work out what the aliens are really up to.
Can Donna stop the Sontarans?
There's only one person who can save the day. But is Donna up to it?
The second half of this two-part adventure rattles along at great pace. And is pretty much action packed from start to finish.
Better still, after helping the Doctor over the last few episodes Donna gets the chance to see if she can do things on her own.
The Doctor's got big problems too, in this episode. Not only is he trying to stop the war-like Sontarans, but he's also doing his best to hold UNIT back from launching what could be a disastrous attack on the aliens.
The Doctor's got BIG problems
This story's anti-war message works well, with the Doctor leading by example as he demonstrates that violence should only ever be used when there's absolutely no alternative.
But it's not all grim fighting, there are some lovely moments of humour, especially for fans who've been watching the series since it came back three years ago.
Some two-part stories promise much in the first-half, but fail to deliver in the second. But the concluding part of this adventure is one that doesn't disappoint.
It's simply a great story, with the Doctor once more taking on deadly opponents armed only with his wits.
And you know that that means the Sontarans don't stand a chance!
Four out of five
"I loved the episode, especially when Donna whacked the Sontaran with the hammer."
Harrison, 11, Hampshire, England
"I think Catherine Tate has ruined it. Dr Who is supposed to be serious, NOT FUNNY!"
James, 12, Staffordshire, England
"I think Doctor Who was terrific. It was a good episode because they had the old enemies back from the old episodes."
Ryan, 12, Oxfordshire, England
"I watched the very new series when it started a few years ago but it just got more boring and weird. Parts may be good but not all of it."
Deniza, 12, Cheshire, England
"I think the poison sky is a great episode but I really can't wait to see the doctors face when he sees his daughter!!!! Doctor Who is the Best show ever!!!!!!"
Lesley, 13, Liverpool, England
"It was the best I have seen this series. I hope the next one is better than this one."
Ellena, 9, Worcestershire, England
"I like Doctor Who because Catherine Tate makes it funny."
Richard, 10, Derbyshire, England
"I think Doctor Who is good but I also think that they should bring back Rose."
Yvonne, 10, Rotherham, England
"I thought Dr Who was really good. It leaves you feeling excited and leaves you thinking... I wonder what's going to happen next?"
Lauren, 12, Cheshire, England
"I loved The Poison Sky, it was one of my fave episodes. When Rose showed up for a split second I was really confused and I loved it when Donna hit a Sontaran in the neck and said 'back of the neck!' It really made me giggle. I hope that the Sontarans will come back and I can't wait to see the doctor's daughter."
Kieran, 12, Taunton, England
"It was great! I loved it, it was really scary when Wilf got locked in the car! Wilf is the best!"
Shirleen, 14, Cardiff, Wales
"I think the Poison Sky was one of the greatest things ever broadcast on TV. General Staal was like a James Bond villain."
Harry, 12, London, England
"I thought this episode was the best episode so far. I really like Donna as the companion. The episode was 10 out of 10. My favourite part was when Donna got the Sontaran on the back of the neck. I still can't believe that you saw Rose on the TARDIS screen."
Amy, 11, Chatham, England
"I liked Poison Sky because the Sontarans are one of my favourite aliens (Daleks are my favourite). The funniest bit was when The Doctor put on a gas mask and said 'Are you my mummy?' I giggled! To explain the episode in one word, sontar-tastic!!!"
James, 10, St. Neots, England
"I thought it was absolutely FANTASTIC. Another sighting of Rose helped the episode move on. Wilfred is so funny. I loved it when Donna's mum got the axe and smashed the car. The best episode of the series so far!! 4.5/5."
Ryan, 13, Oxford, England
"I just watched Doctor Who and I am dying to find out more about the next episode, The Doctor's Daughter. I am so on the edge of my seat!"
Chloe, 12, Littlehampton, England
"I think this was the best episode apart from the one in Pompeii. It was more exiting and Donna did a bit more action."
Agatha, 9, London, England
"Great episode. I thought the Sontarans were great monsters, I say bring them in the finale and make them fight the Daleks."
Thomas, 10, Merseyside, England
"I thought this was one of the scariest episodes yet. I loved the part when the Doctor pulled the thingy off of the real Martha's head and the other one (the fake/clone) flopped to the floor."
Ben, 10, Manchester, England
"I think Donna is a great companion for the Doctor and she is hilarious, also I wish Rose could come back. I am a big fan of Doctor Who."
Saamiya, 12, London, England
"This episode was so cool. I wonder why the Tardis was so out of control? Well, we'll find out soon!"
Hannah, 11, Essex, England
"I thought it was great. My favourite bit was when the Tardis doors closed and it flew off by itself."
Luke, 9, Durham, England
"That was one of the best episodes ever! I mean the Sontaran Stratagem left off with Donna's granddad (Wilf) choking in the car, an evil clone Martha infiltrating UNIT (Unified Intelligence Taskforce) and the Sontarans and Luke taking over the Earth! Phew!
The Doctor's in a bit of a sticky position! I LOVED the part when Sylvia (Donna's mum) got the axe and shattered the windscreen of her car to get Wilf out. I think that the clone Martha was just evil! But she turned good in the end.
I'm glad Luke turned into a goodie when he sacrificed himself for the Doctor and the planet, and killed the Sontarans. I thought it was when the Doctor changed channels to Tommy Zoom and kept annoying general Staal.
Did you see the next time??????? I can't believe the Doctor has a daughter, and rather appropriately, the actress who is playing her is the real-life daughter of Peter Davidson, the fifth Doctor himself!
I thought Catherine Tate's performance was brilliant, really emotional! Glad that Martha's coming back for another trip in the TARDIS!!FABULOUS,BRILLIANT episode!!!"
Minoli, 11years 4months 4 days, Ilford, England
"It was good, but not the best so far. What I really liked was Martha becoming cloned."
Josh, 13, Sheffield, England
"I don't think Donna should be in it. She is not the right type and I think Rose should come back and stay."
Andrew, 11, St Ives, England
"Wow! We had another glimpse of Rose, and Martha is trapped in the Tardis with the Doctor and Donna! I can't believe the Doctor has a daughter!!!"
Ramla, 13, Sheffield, England
"I thought it was GREAT! I love Donna though, she's really good at acting."
Bridget, 10, Clayton, England
"Wow!! SUCH A GOOD EPISODE!!! How funny was it when the Doctor went, 'Are you my mummy?'. Me and my family couldn't stop laughing!!! And when Rose appeared on the Tardis screen, I screamed!!!"
Filippa, 13, Leeds, England
"It was a lot better than the first of the two-parter, I really enjoyed it. The Doctor's daughter, ooh, sounds good!"
Aisling, 9, Cheltenham, England
"I thought that it was amazing. I noticed Rose on the TARDIS screen."
Ben, 11, Rugeley, England
"I loved this episode of Doctor Who. My best bits were: 1 - When the Doctor was wearing the gas mask and he goes, 'Are you my mummy?' 2 - When Donna arrives back on Earth and gives the doctor a hug going, 'I really hate you'."
Jackie, 11, Cheshire, England
"Brilliantly paced episode. I loved every minute of it! I liked the fact it was a lot more action packed than other episodes. It felt like a big epic battle scene out of Star Wars."
Daniel, 12, Birmingham, England
"I thought 'The Poison Sky' was really good! I really liked the granddad and the man who was General Staal! I was pleased that Luke died as he was a bad actor and annoying! Next week looks brilliant "
David, 13, Cambridge, England
"The next time was the real shocker. But it was great that the Doctor knew Martha was a clone, but so sad when they thought he was going to die. Doctor who is awesome."
Vicki, 14, Cambridge, England