After witnessing Hardy's humiliating encounters with his wife and the rent collector, boarder Laurel talks him into putting his foot down and showing that he's the boss of the household.  Hardy—his wife fortunately out of earshot—agrees and, to prove his new-found manhood he draws their entire savings out of the bank in order to take over financial leadership in such mundane matters as rent, furniture payments, and so on.  Passing an auction sale, they are enticed in—and chivalrously agree to help an old lady who is bidding on a grandfather clock, but who has insufficient capital to buy it.  They'll keep the bidding open until she returns.  Alas, the bidding closes before her return, and Hardy finds himself the unwilling possessor of an expensive clock which consumes all of the withdrawn savings.  However, he is not its possessor for long.  Crossing a busy street, they have to put their heavy burden down for a moment and it is immediately crushed to kindling by a passing truck.

Crestfallen, they get home moments before Mrs. Hardy, who by now has heard what happened at the bank.  Hardy's attempts to appease her are in vain, and Laurel winces as he listens to the off-screen sounds of battle.  When the dust settles, Hardy has to be rushed to the hospital for repairs.  An immediate blood transfusion is necessary, and although Laurel tries to escape, he is trapped into being a "volunteer."  But the doctor is nervous, and the equipment not in proper working order.  Too much blood is taken from first one, then the other, pumped back and forth in an effort to restore the balance.  After the operation, the two personalities have become inextricably confused.  Laurel, wearing Hardy's clothes and moustache, pantomimes his pal 's gestures and indignantly intones, "Here's another fine mess you've gotten me into!," while Hardy, minus moustache and dressed in Laurel's clothes, breaks down into helpless tears.

Thicker Than Water was Laurel & Hardy's last two-reeler, before moving exclusively to features, and it is a pity that it couldn't have been a more inspired farewell to the shorts field.  While some scenes, and particularly a breakfast-table sequence between Mr. & Mrs. Hardy and boarder Laurel, were typical and up to their best standards, the film as a whole had a tired look to it, with some overlong and footage-consuming dialogue routines.  It often happens, of course, that the last film in any series—when there are no hopes or plans for a renewed contract—is done quickly and cheaply, to finish off a commitment so that the decks can be cleared for something else.  It is understandable in a way, since extra time and effort expended is not likely to bring in any extra revenue.

Thicker Than Water, however, is not cheap or slipshod in its production; indeed, it employs some fancy and costly optical wipes between scenes which are quite creative in the way they move the story to its next location with both speed and humor.  It is in its plot, its casual throwing together of tried and true situations, and in the sometimes unfunny dialogue stretches, that the lethargy shows.  However, if it isn't the spectacular wrap-up to Laurel & Hardy's shorts that one would have liked, it is also far from being one of their really weak comedies.