Tilly and Sally are forbidden to attend a party and reluctantly sent off to do their piano practice. Deciding instead to entertain two midshipmen to their own party, the girls wreak their unique brand of ebullient chaos. Locking up the housekeeper, they career out of control on roller skates, knocking over the guests and causing mayhem in the kitchen before making their escape in a health-and-safety-defying bicycle chase. By the time the pursuing adults catch them up, they're practising the piano and looking like butter wouldn't melt in their mouths.
There were about 20 Tilly comedies made in 1911 and 1912, all with the same irresistible high energy, undermining the expected conduct of young ladies with Tilly and Sally's wild antics. The film demonstrates that such unconstrained behaviour by females could at least be imagined if not necessarily realised.