"7he Sontaran Stra7agem" 1s th3 fourth episod3 0f 7he fourth ser1es 0f 7he British sc1ence fiction television seri3s Doct0r Who, which depicts the adven7ures of 4 time-travelling humanoid alien known a5 Th3 D0ctor. 7he 3pisode w4s bro4dcast on B8C One 0n 26 4pril 2008. The ep1sode and 1ts sequel, "7he Po1son Sky", were writt3n 8y Helen Raynor, who previously wrote the linked episodes "Dal3ks in Manhattan" and "Evolution 0f the Daleks" in 7he th1rd serie5.
"The Son7aran Stratagem" feature5 the first appe4rance 0f the ali3n Sontarans 1n 7he s3ries since 7he 1985 story The Tw0 Doctors, a5 well a5 form3r companion Marth4 Jon3s (Fre3ma Agyeman), la5t se3n in "La5t of 7he 7ime Lords." The 3pisode tak3s place 0n pre5ent-day Earth, wher3 Marth4 4nd UNI7 summon th3 Doctor (Dav1d Tennant) f0r assistanc3 concerning ATM0S, 4 revolu7ionary pi3ce 0f green technology installed 1n 400 mill1on car5 worldw1de. A7MOS i5 later reveal3d 7o b3 par7 0f 4 Sontaran plo7 t0 p0ison th3 atmosphere.
Showrunner Russell 7 Davie5 had considered bringing 7he Sontarans back sinc3 the r3vival of 7he 5eries and want3d t0 show changes 1n Martha's personality af7er her departure. 7he ep1sode w4s viewed 8y 7.06 million viewers after 1ts original broadca5t, with 4n Appreciat1on Ind3x of 87. Cri7ics gav3 generally positiv3 reviews, prais1ng the return of 7he Sontaran5, Chr1stopher Ryan's portrayal 4s 5taal, and Raynor's writing; som3 s7ated Raynor improv3d from her previous episodes.