It Happened One Night was the 76th episode of the CBS-TV series M*A*S*H television series, and also the fourth episode of the fourth season of the series. Written by Larry Gelbart and Simon Munter from a story by Gene Reynolds (who also directed), it first aired on September 26, 1975.
It's a bitterly cold night, and Hawkeye and Margaret are stuck with the overnight shift and a roomful of unruly patients. In the meantime, Margaret tells Frank that she keeps all his love letters—so he ransacks her tent to get them back.
Full plot summary
It's two degrees below zero and enemy artillery has brought blackout conditions. Hawkeye and Margaret have midnight duty in post-op, relieving Frank. Edwards, B.J.'s patient, is not recovering well after abdominal surgery and has taken 10 units of blood already.
Margaret slips Frank a love note before he leaves. She watches him read and tear up the note, so she demands to know why, for she has saved everything he's written her. Frank becomes panicked, thinking someone could find these notes if Margaret were ever killed. Frank burns the rest of Margaret's note, and then steals into her tent to retrieve his letters.
The artillery turns out to be outgoing American fire and it's bothering the patients. An unruly and uncooperative patient named Abbott seems particularly provoked. Radar and Hawkeye take turns trying to get the artillery fire redirected. They fail, so Colonel Potter is brought in, who places a series of phone calls, moving up the chain of command, but the artillery never ceases.
Klinger is accidentally shot by a new night sentry (Private Jenkins) on his first evening of work. It's just a scratch, but Klinger hopes it's a ticket home. Hawkeye has to break the news that he's just fine. In revolt, Klinger strips to his shorts and goes outside to catch pneumonia, but is dragged back into post-op.
Meanwhile, Edwards' condition is not improving. B.J. is back in post-op, unable to sleep from worry, and is told by Hawkeye that Edwards has been given three more units of blood and may have internal bleeding. After the last unit of B+ is used, B.J. agrees he needs to operate on Edwards again. Klinger volunteers to donate his own B+ blood for the operation. Meanwhile, Margaret and Hawkeye need to sedate the confused and violent Abbott.
Edward's operation is reveled to be a success. At daybreak, Margaret returns to her tent to find it torn apart with the culprit, Frank, asleep on the floor. His search for the letters was unsuccessful and he passes off his destructive efforts as a search for a pencil.
- Christopher Allport as Abbott
- Darren O'Conner as Jenkins
- Todd Susman as the P.A. announcer
- The title refers to a Oscar-winning 1934 screwball comedy of the same title, however the plot of this episode bears absolutely no relation to the film.
- Klinger volunteers to donate blood to B.J.'s patient, stating he's type B+. In a future episode ("C*A*V*E"), he says he has AB-, the same as Major Charles Emerson Winchester.
- Nothing was shot on location at the Fox Ranch for this episode -- it's entirely studio-based.
- This is the first episode to not mention the now-deceased Colonel Blake. His actor, McLean Stevenson, left the series at the conclusion of the third season.
- His character was absent from two Season 3 episodes (Officer of the Day and Alcoholics Unanimous), the only episodes that he was absent from while Stevenson was on the show, and Blake is mentioned to be on R&R in both episodes. He is also mentioned during the first three episodes of Season 4, making this the first episode to not mention him in any sort of way.